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Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2018 $ / shares shares
Entity Registrant Name	SIMON PROPERTY GROUP INC /DE/
Entity Central Index Key	0001063761
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Common stock
Entity Common Stock, Shares Outstanding \| shares	309,296,415
Entity Listing, Par Value Per Share \| $ / shares	$ 0.0001
Class B common stock
Entity Common Stock, Shares Outstanding \| shares	8,000
Entity Listing, Par Value Per Share \| $ / shares	$ 0.0001

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
ASSETS:
Investment properties, at cost	$ 36,943,299	$ 36,393,464
Less - accumulated depreciation	12,638,409	11,935,949
Investment properties at cost, net	24,304,890	24,457,515
Cash and cash equivalents	695,718	1,482,309
Tenant receivables and accrued revenue, net	722,730	742,672
Investment in unconsolidated entities, at equity	2,281,688	2,266,483
Investment in Klepierre, at equity	1,776,655	1,934,676
Deferred costs and other assets	1,298,012	1,373,983
Total assets	31,079,693	32,257,638
LIABILITIES:
Mortgages and unsecured indebtedness	23,678,264	24,632,463
Accounts payable, accrued expenses, intangibles, and deferred revenues	1,268,099	1,269,190
Cash distributions and losses in unconsolidated entities, at equity	1,534,550	1,406,378
Other liabilities	503,342	520,363
Total liabilities	26,984,255	27,828,394
Commitments and contingencies
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties	197,937	190,480
Capital stock (850,000,000 total shares authorized, $0.0001 par value, 238,000,000 shares of excess common stock, 100,000,000 authorized shares of preferred stock):
Capital in excess of par value	9,736,720	9,614,748
Accumulated deficit	(4,896,754)	(4,782,173)
Accumulated other comprehensive loss	(118,593)	(110,453)
Common stock held in treasury, at cost, 11,115,156 and 9,163,920 shares, respectively	(1,380,619)	(1,079,063)
Total stockholders' equity	3,383,616	3,686,168
Noncontrolling interests	513,885	552,596
Total equity	3,897,501	4,238,764
Total liabilities and equity	31,079,693	32,257,638
Simon Property Group, L.P.
ASSETS:
Investment properties, at cost	36,943,299	36,393,464
Less - accumulated depreciation	12,638,409	11,935,949
Investment properties at cost, net	24,304,890	24,457,515
Cash and cash equivalents	695,718	1,482,309
Tenant receivables and accrued revenue, net	722,730	742,672
Investment in unconsolidated entities, at equity	2,281,688	2,266,483
Investment in Klepierre, at equity	1,776,655	1,934,676
Deferred costs and other assets	1,298,012	1,373,983
Total assets	31,079,693	32,257,638
LIABILITIES:
Mortgages and unsecured indebtedness	23,678,264	24,632,463
Accounts payable, accrued expenses, intangibles, and deferred revenues	1,268,099	1,269,190
Cash distributions and losses in unconsolidated entities, at equity	1,534,550	1,406,378
Other liabilities	503,342	520,363
Total liabilities	26,984,255	27,828,394
Commitments and contingencies
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties	197,937	190,480
Capital stock (850,000,000 total shares authorized, $0.0001 par value, 238,000,000 shares of excess common stock, 100,000,000 authorized shares of preferred stock):
Preferred units, 796,948 units outstanding. Liquidation value of $39,847	42,830	43,077
General Partner, 309,304,415 and 311,166,854 units outstanding, respectively	3,340,786	3,643,091
Limited Partners, 47,212,857 and 46,879,625 units outstanding, respectively	509,943	548,858
Total partners' equity	3,893,559	4,235,026
Nonredeemable noncontrolling interests in properties, net	3,942	3,738
Total equity	3,897,501	4,238,764
Total liabilities and equity	31,079,693	32,257,638
Series J Preferred stock
Capital stock (850,000,000 total shares authorized, $0.0001 par value, 238,000,000 shares of excess common stock, 100,000,000 authorized shares of preferred stock):
Series J 8 3/8% cumulative redeemable preferred stock, 1,000,000 shares authorized, 796,948 issued and outstanding with a liquidation value of $39,847	42,830	43,077
Common stock
Capital stock (850,000,000 total shares authorized, $0.0001 par value, 238,000,000 shares of excess common stock, 100,000,000 authorized shares of preferred stock):
Common stock	32	32
Class B common stock
Capital stock (850,000,000 total shares authorized, $0.0001 par value, 238,000,000 shares of excess common stock, 100,000,000 authorized shares of preferred stock):
Common stock

Unaudited Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Capital stock, total shares authorized	850,000,000	850,000,000
Capital stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Capital stock, shares of excess common stock	238,000,000	238,000,000
Capital stock, authorized shares of preferred stock	100,000,000	100,000,000
Common stock held in treasury, shares	11,115,156	9,163,920
Series J Preferred stock
Preferred stock stated dividend rate percentage	8.375%	8.375%
Series J 8 3/8% cumulative redeemable preferred stock, shares authorized	1,000,000	1,000,000
Series J 8 3/8% cumulative redeemable preferred stock, shares issued	796,948	796,948
Series J 8 3/8% cumulative redeemable preferred stock, shares outstanding	796,948	796,948
Preferred units, Liquidation value (in dollars)	$ 39,847	$ 39,847
Common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	511,990,000	511,990,000
Common stock, shares issued	320,411,571	320,322,774
Common stock, shares outstanding	320,411,571	320,322,774
Class B common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	10,000	10,000
Common stock, shares issued	8,000	8,000
Common stock, shares outstanding	8,000	8,000
Simon Property Group, L.P.
Preferred units, units outstanding	796,948	796,948
Preferred units, Liquidation value (in dollars)	$ 39,847	$ 39,847
General Partner, units outstanding	309,304,415	311,166,854
Limited Partners, units outstanding	47,212,857	46,879,625

Unaudited Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
REVENUE:
Minimum rent	$ 864,514	$ 861,184	$ 2,581,792	$ 2,559,535
Overage rent	39,601	36,634	104,533	94,601
Tenant reimbursements	385,543	386,713	1,138,855	1,146,156
Management fees and other revenues	28,784	28,946	85,506	90,860
Other income	90,563	90,161	286,491	219,796
Total revenue	1,409,005	1,403,638	4,197,177	4,110,948
EXPENSES:
Property operating	119,021	118,807	335,420	330,226
Depreciation and amortization	316,175	317,037	953,309	950,265
Real estate taxes	119,315	111,953	344,950	332,027
Repairs and maintenance	23,632	25,352	73,507	72,654
Advertising and promotion	36,688	36,006	107,979	108,450
Provision for credit losses	4,984	2,895	13,915	10,765
Home and regional office costs	32,714	31,451	106,093	110,906
General and administrative	12,172	13,014	35,713	40,089
Other	26,913	57,055	69,293	102,678
Total operating expenses	691,614	713,570	2,040,179	2,058,060
OPERATING INCOME	717,391	690,068	2,156,998	2,052,888
Interest expense	(199,469)	(199,032)	(611,585)	(604,408)
Loss on extinguishment of debt				(128,618)
Income and other taxes	(10,118)	(14,511)	(26,475)	(16,981)
Income from unconsolidated entities	134,408	116,110	325,263	277,212
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net			144,949	4,989
CONSOLIDATED NET INCOME	642,212	592,635	1,989,150	1,585,082
Net income (loss) attributable to noncontrolling interests	85,111	78,018	262,722	209,070
Preferred dividends	834	834	2,503	2,503
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS	$ 556,267	$ 513,783	$ 1,723,925	$ 1,373,509
BASIC AND DILUTED EARNINGS PER COMMON SHARE or UNIT:
Net income attributable to common stockholders or unitholders (in dollars per share or unit)	$ 1.80	$ 1.65	$ 5.57	$ 4.41
Consolidated Net Income	$ 642,212	$ 592,635	$ 1,989,150	$ 1,585,082
Unrealized gain (loss) on derivative hedge agreements	5,241	(8,598)	20,355	(31,396)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings	1,591	(19,362)	5,929	(14,303)
Currency translation adjustments	(10,763)	12,922	(35,797)	42,815
Changes in available-for-sale securities and other	(22)	6,787	(88)	6,324
Comprehensive income	638,259	584,384	1,979,549	1,588,522
Comprehensive income attributable to noncontrolling interests	84,466	76,935	261,260	209,424
Comprehensive income attributable to common stockholders or unitholders	553,793	507,449	1,718,289	1,379,098
Simon Property Group, L.P.
REVENUE:
Minimum rent	864,514	861,184	2,581,792	2,559,535
Overage rent	39,601	36,634	104,533	94,601
Tenant reimbursements	385,543	386,713	1,138,855	1,146,156
Management fees and other revenues	28,784	28,946	85,506	90,860
Other income	90,563	90,161	286,491	219,796
Total revenue	1,409,005	1,403,638	4,197,177	4,110,948
EXPENSES:
Property operating	119,021	118,807	335,420	330,226
Depreciation and amortization	316,175	317,037	953,309	950,265
Real estate taxes	119,315	111,953	344,950	332,027
Repairs and maintenance	23,632	25,352	73,507	72,654
Advertising and promotion	36,688	36,006	107,979	108,450
Provision for credit losses	4,984	2,895	13,915	10,765
Home and regional office costs	32,714	31,451	106,093	110,906
General and administrative	12,172	13,014	35,713	40,089
Other	26,913	57,055	69,293	102,678
Total operating expenses	691,614	713,570	2,040,179	2,058,060
OPERATING INCOME	717,391	690,068	2,156,998	2,052,888
Interest expense	(199,469)	(199,032)	(611,585)	(604,408)
Loss on extinguishment of debt				(128,618)
Income and other taxes	(10,118)	(14,511)	(26,475)	(16,981)
Income from unconsolidated entities	134,408	116,110	325,263	277,212
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net			144,949	4,989
CONSOLIDATED NET INCOME	642,212	592,635	1,989,150	1,585,082
Net income (loss) attributable to noncontrolling interests	497	(550)	684	(721)
Preferred dividends	1,313	1,313	3,939	3,939
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS	640,402	591,872	1,984,527	1,581,864
NET INCOME ATTRIBUTABLE TO UNITHOLDERS ATTRIBUTABLE TO:
General Partner	556,267	513,783	1,723,925	1,373,509
Limited Partners	$ 84,135	$ 78,089	$ 260,602	$ 208,355
BASIC AND DILUTED EARNINGS PER COMMON SHARE or UNIT:
Net income attributable to common stockholders or unitholders (in dollars per share or unit)	$ 1.80	$ 1.65	$ 5.57	$ 4.41
Consolidated Net Income	$ 642,212	$ 592,635	$ 1,989,150	$ 1,585,082
Unrealized gain (loss) on derivative hedge agreements	5,241	(8,598)	20,355	(31,396)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings	1,591	(19,362)	5,929	(14,303)
Currency translation adjustments	(10,763)	12,922	(35,797)	42,815
Changes in available-for-sale securities and other	(22)	6,787	(88)	6,324
Comprehensive income	638,259	584,384	1,979,549	1,588,522
Comprehensive income attributable to noncontrolling interests	318	316	1,063	1,388
Comprehensive income attributable to common stockholders or unitholders	$ 637,941	$ 584,068	$ 1,978,486	$ 1,587,134

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Consolidated Net Income	$ 1,989,150	$ 1,585,082
Adjustments to reconcile consolidated net income to net cash provided by operating activities -
Depreciation and amortization	1,009,671	1,012,335
Loss on debt extinguishment		128,618
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net	(144,949)	(4,989)
Gains on sales of marketable securities		(21,541)
Unrealized change in fair value of equity instruments	(1,212)
Gain on interest in unconsolidated entity (Note 5)	(35,621)
Straight-line rent	(14,923)	(21,433)
Equity in income of unconsolidated entities	(325,263)	(277,212)
Distributions of income from unconsolidated entities	289,411	270,938
Changes in assets and liabilities -
Tenant receivables and accrued revenue, net	27,668	19,925
Deferred costs and other assets	(74,922)	(75,688)
Accounts payable, accrued expenses, intangibles, deferred revenues and other liabilities	32,156	103,418
Net cash provided by operating activities	2,751,166	2,719,453
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions		(87,741)
Funding of loans to related parties	(4,641)	(68,206)
Capital expenditures, net	(585,957)	(487,321)
Cash impact from the consolidation of properties	11,276	7,536
Investments in unconsolidated entities	(51,883)	(111,225)
Purchase of marketable and non-marketable securities	(23,273)	(5,503)
Proceeds from sales of marketable and non-marketable securities		53,923
Insurance proceeds for property restoration	16,160
Distributions of capital from unconsolidated entities and other	428,862	331,693
Net cash used in investing activities	(209,456)	(366,844)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from sales of common stock, units and other, net of transaction costs	(247)	(246)
Purchase of shares or units related to stock grant recipients' tax withholdings	(2,911)	(2,789)
Redemption of limited partner units	(7,619)
Purchase of treasury stock	(307,296)	(396,169)
Distributions to noncontrolling interest holders in properties	(11,524)	(8,936)
Contributions from noncontrolling interest holders in properties	161	289
Preferred distributions of the Operating Partnership	(1,436)	(1,436)
Distributions to stockholders and preferred dividends	(1,829,610)	(1,655,307)
Distributions to limited partners	(276,530)	(251,066)
Loss on debt extinguishment		(128,618)
Proceeds from issuance of debt, net of transaction costs	5,895,653	8,071,035
Repayments of debt	(6,786,942)	(8,031,020)
Net cash used in financing activities	(3,328,301)	(2,404,263)
DECREASE IN CASH AND CASH EQUIVALENTS	(786,591)	(51,654)
CASH AND CASH EQUIVALENTS, beginning of period	1,482,309	560,059
CASH AND CASH EQUIVALENTS, end of period	695,718	508,405
Simon Property Group, L.P.
CASH FLOWS FROM OPERATING ACTIVITIES:
Consolidated Net Income	1,989,150	1,585,082
Adjustments to reconcile consolidated net income to net cash provided by operating activities -
Depreciation and amortization	1,009,671	1,012,335
Loss on debt extinguishment		128,618
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net	(144,949)	(4,989)
Gains on sales of marketable securities		(21,541)
Unrealized change in fair value of equity instruments	(1,212)
Gain on interest in unconsolidated entity (Note 5)	(35,621)
Straight-line rent	(14,923)	(21,433)
Equity in income of unconsolidated entities	(325,263)	(277,212)
Distributions of income from unconsolidated entities	289,411	270,938
Changes in assets and liabilities -
Tenant receivables and accrued revenue, net	27,668	19,925
Deferred costs and other assets	(74,922)	(75,688)
Accounts payable, accrued expenses, intangibles, deferred revenues and other liabilities	32,156	103,418
Net cash provided by operating activities	2,751,166	2,719,453
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions		(87,741)
Funding of loans to related parties	(4,641)	(68,206)
Capital expenditures, net	(585,957)	(487,321)
Cash impact from the consolidation of properties	11,276	7,536
Investments in unconsolidated entities	(51,883)	(111,225)
Purchase of marketable and non-marketable securities	(23,273)	(5,503)
Proceeds from sales of marketable and non-marketable securities		53,923
Insurance proceeds for property restoration	16,160
Distributions of capital from unconsolidated entities and other	428,862	331,693
Net cash used in investing activities	(209,456)	(366,844)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from sales of common stock, units and other, net of transaction costs	(247)	(246)
Purchase of shares or units related to stock grant recipients' tax withholdings	(2,911)	(2,789)
Redemption of limited partner units	(7,619)
Purchase of general partner units	(307,296)	(396,169)
Distributions to noncontrolling interest holders in properties	(11,524)	(8,936)
Contributions from noncontrolling interest holders in properties	161	289
Preferred distributions of the Operating Partnership	(2,107,576)	(1,907,809)
Loss on debt extinguishment		(128,618)
Proceeds from issuance of debt, net of transaction costs	5,895,653	8,071,035
Repayments of debt	(6,786,942)	(8,031,020)
Net cash used in financing activities	(3,328,301)	(2,404,263)
DECREASE IN CASH AND CASH EQUIVALENTS	(786,591)	(51,654)
CASH AND CASH EQUIVALENTS, beginning of period	1,482,309	560,059
CASH AND CASH EQUIVALENTS, end of period	$ 695,718	$ 508,405

Organization	9 Months Ended
Organization	Sep. 30, 2018
Organization
Organization	1. Organization Simon Property Group, Inc. is a Delaware corporation that operates as a self-administered and self-managed real estate investment trust, or REIT, under the Internal Revenue Code of 1986, as amended, or the Internal Revenue Code. REITs will generally not be liable for U.S. federal corporate income taxes as long as they distribute not less than 100% of their REIT taxable income. Simon Property Group, L.P. is our majority-owned Delaware partnership subsidiary that owns all of our real estate properties and other assets. In these condensed notes to the consolidated financial statements, unless stated otherwise or the context otherwise requires, references to "Simon" mean Simon Property Group, Inc. and references to the "Operating Partnership" mean Simon Property Group, L.P. References to "we," "us" and "our" mean collectively Simon, the Operating Partnership and those entities/subsidiaries owned or controlled by Simon and/or the Operating Partnership. Unless otherwise indicated, these condensed notes to consolidated financial statements apply to both Simon and the Operating Partnership. According to the Operating Partnership's partnership agreement, the Operating Partnership is required to pay all expenses of Simon. We own, develop and manage premier shopping, dining, entertainment and mixed-use destinations, which consist primarily of malls, Premium Outlets®, and The Mills®. As of September 30, 2018, we owned or held an interest in 207 income‑producing properties in the United States, which consisted of 107 malls, 69 Premium Outlets, 14 Mills, four lifestyle centers, and 13 other retail properties in 37 states and Puerto Rico. Internationally, as of September 30, 2018, we had ownership interests in nine Premium Outlets in Japan, four Premium Outlets in South Korea, three Premium Outlets in Canada, two Premium Outlets in Malaysia and one Premium Outlet in Mexico. We also own an interest in eight Designer Outlet properties in Europe, of which six properties are consolidated, and one Designer Outlet property in Canada. Of the eight properties in Europe, two are located in Italy, two are located in the Netherlands and one each is located in Austria, Germany, France and the United Kingdom. As of September 30, 2018, we also owned a 21.2% equity stake in Klépierre SA, or Klépierre, a publicly traded, Paris‑based real estate company which owns, or has an interest in, shopping centers located in 16 countries in Europe.

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2018
Basis of Presentation
Basis of Presentation	2. Basis of Presentation The accompanying unaudited consolidated financial statements include the accounts of all controlled subsidiaries, and all significant intercompany amounts have been eliminated. Due to the seasonal nature of certain operational activities, the results for the interim periods ended September 30, 2018 are not necessarily indicative of the results to be expected for the full year. These consolidated financial statements have been prepared in accordance with the instructions to Form 10‑Q and include all of the information and disclosures required by accounting principles generally accepted in the United States (GAAP) for interim reporting. Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments necessary for fair presentation (including normal recurring accruals) have been included. The consolidated financial statements in this Form 10‑Q should be read in conjunction with the audited consolidated financial statements and related notes contained in the combined 2017 Annual Report on Form 10‑K of Simon and the Operating Partnership. As of September 30, 2018, we consolidated 135 wholly‑owned properties and 19 additional properties that are less than wholly‑owned, but which we control or for which we are the primary beneficiary. We account for the remaining 81 properties, or the joint venture properties, as well as our investments in Klépierre, Aéropostale, Authentic Brands Group, LLC, or ABG, and HBS Global Properties, or HBS, using the equity method of accounting, as we have determined we have significant influence over their operations. We manage the day‑to‑day operations of 57 of the 81 joint venture properties, but have determined that our partner or partners have substantive participating rights with respect to the assets and operations of these joint venture properties. Our investments in joint ventures in Japan, South Korea, Mexico, Malaysia, Germany, Canada, and the United Kingdom comprise 20 of the remaining 24 properties. These international properties are managed by joint ventures in which we share control. Preferred distributions of the Operating Partnership are accrued at declaration and represent distributions on outstanding preferred units of partnership interests, or preferred units, and are included in net income attributable to noncontrolling interests. We allocate net operating results of the Operating Partnership after preferred distributions to limited partners and to Simon based on the partners’ respective weighted average ownership interests in the Operating Partnership. Net operating results of the Operating Partnership attributable to limited partners are reflected in net income attributable to noncontrolling interests. Simon’s weighted average ownership interest in the Operating Partnership was 86.9% and 86.8% for the nine months ended September 30, 2018 and 2017, respectively. As of September 30, 2018 and December 31, 2017, Simon’s ownership interest in the Operating Partnership was 86.8% and 86.9%, respectively. We adjust the noncontrolling limited partners’ interests at the end of each period to reflect their interest in the net assets of the Operating Partnership. Preferred unit requirements in the Operating Partnership’s accompanying consolidated statements of operations and comprehensive income represent distributions on outstanding preferred units and are recorded when declared.

Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Significant Accounting Policies

Significant Accounting Policies

3. Significant Accounting Policies

Cash and Cash Equivalents

We consider all highly liquid investments purchased with an original maturity of 90 days or less to be cash and cash equivalents. Cash equivalents are carried at cost, which approximates fair value. Cash equivalents generally consist of commercial paper, bankers’ acceptances, Eurodollars, repurchase agreements, and money market deposits or securities. Financial instruments that potentially subject us to concentrations of credit risk include our cash and cash equivalents and our trade accounts receivable. We place our cash and cash equivalents with institutions of high credit quality. However, at certain times, such cash and cash equivalents are in excess of Federal Deposit Insurance Corporation and Securities Investor Protection Corporation insurance limits.

Equity Instruments and Debt Securities

Equity instruments and debt securities consist primarily of the debt securities of our captive insurance subsidiary, equity instruments, our deferred compensation plan investments, and certain investments held to fund the debt service requirements of debt previously secured by investment properties. At September 30, 2018 and December 31, 2017, we had equity instruments with readily determinable fair values of $97.2 million and $88.3 million, respectively. Effective January 1, 2018, changes in fair value of these equity instruments are recorded in earnings. At September 30, 2018 and December 31, 2017, we had equity instruments without readily determinable fair values of $176.4 million and $186.9 million, respectively, for which we have elected the measurement alternative. We regularly evaluate these investments for any impairment in their estimated fair value, as well as any observable price changes for an identical or similar equity instrument of the same issuer, and determined that no material adjustment in the carrying value was required for the three or nine months ended September 30, 2018.

Our deferred compensation plan equity instruments are valued based upon quoted market prices. The investments have a matching liability as the amounts are fully payable to the employees that earned the compensation. Changes in value of these securities and changes to the matching liability to employees are both recognized in earnings and, as a result, there is no impact to consolidated net income.

On July 26, 2017, we sold our investment in certain equity instruments. The aggregate proceeds received from the sale were $53.9 million, and we recognized a gain on the sale of $21.5 million, which is included in other income in the accompanying consolidated statements of operations and comprehensive income for the three and nine months ended September 30, 2017.

At September 30, 2018 and December 31, 2017, we held debt securities of $66.8 million and $55.7 million, respectively, in our captive insurance subsidiary. The types of securities included in the investment portfolio of our captive insurance subsidiary are typically U.S. Treasury or other U.S. government securities as well as corporate debt securities with maturities ranging from less than 1 year to 10 years. These securities are classified as available‑for‑sale and are valued based upon quoted market prices or other observable inputs when quoted market prices are not available. The amortized cost of debt securities, which approximates fair value, held by our captive insurance subsidiary is adjusted for amortization of premiums and accretion of discounts to maturity. Changes in the values of these securities are recognized in accumulated other comprehensive income (loss) until the gain or loss is realized or until any unrealized loss is deemed to be other‑than‑temporary. We review any declines in value of these securities for other‑than‑temporary impairment and consider the severity and duration of any decline in value. To the extent an other‑than‑temporary impairment is deemed to have occurred, an impairment is recorded and a new cost basis is established.

Our captive insurance subsidiary is required to maintain statutory minimum capital and surplus as well as maintain a minimum liquidity ratio. Therefore, our access to these securities may be limited.

Fair Value Measurements

Level 1 fair value inputs are quoted prices for identical items in active, liquid and visible markets such as stock exchanges. Level 2 fair value inputs are observable information for similar items in active or inactive markets, and appropriately consider counterparty creditworthiness in the valuations. Level 3 fair value inputs reflect our best estimate of inputs and assumptions market participants would use in pricing an asset or liability at the measurement date. The inputs are unobservable in the market and significant to the valuation estimate. We have no investments for which fair value is measured on a recurring basis using Level 3 inputs.

The equity instruments with readily determinable fair values we held at September 30, 2018 and December 31, 2017 were primarily classified as having Level 1 and Level 2 fair value inputs. In addition, we had derivative instruments which were classified as having Level 2 inputs, which consist primarily of foreign currency forward contracts and interest rate swap agreements with a gross asset balance of $12.9 million at September 30, 2018 and a gross liability balance of $8.6 million and $18.1 million at September 30, 2018 and December 31, 2017, respectively.

Note 6 includes a discussion of the fair value of debt measured using Level 2 inputs. Level 3 inputs to our purchase accounting and impairment analyses include our estimations of net operating results of the property, capitalization rates and discount rates.

Noncontrolling Interests

Simon

Details of the carrying amount of our noncontrolling interests are as follows:


	As of		As of
	September 30,		December 31,
	2018		2017
Limited partners’ interests in the Operating Partnership	$	509,943	$	548,858
Nonredeemable noncontrolling interests in properties, net		3,942		3,738
Total noncontrolling interests reflected in equity	$	513,885	$	552,596

Net income attributable to noncontrolling interests (which includes nonredeemable and redeemable noncontrolling interests in consolidated properties, limited partners’ interests in the Operating Partnership and preferred distributions payable by the Operating Partnership on its outstanding preferred units) is a component of consolidated net income. In addition, the individual components of other comprehensive income (loss) are presented in the aggregate for both controlling and noncontrolling interests, with the portion attributable to noncontrolling interests deducted from comprehensive income attributable to common stockholders.

A rollforward of noncontrolling interests is as follows:


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling interests, beginning of period	$	507,604		564,444	$	552,596	$	649,464
Net income attributable to noncontrolling interests after preferred distributions and income attributable to redeemable noncontrolling interests in consolidated properties		84,452		78,405		261,665		209,743
Distributions to noncontrolling interest holders		(93,637)		(86,125)		(277,550)		(254,026)
Other comprehensive (loss) income allocable to noncontrolling interests:
Unrealized gain (loss) on derivative hedge agreements		717		(1,135)		2,710		(4,116)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings		214		(2,555)		785		(1,887)
Currency translation adjustments		(1,573)		1,712		(4,944)		5,511
Changes in available-for-sale securities and other		(3)		895		(12)		846
		(645)		(1,083)		(1,461)		354
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership		(74,990)		(7,350)		(127,707)		(75,685)
Units issued to limited partners		84,103		—		84,103		—
Units exchanged for common shares		(934)		(252)		(1,004)		(1,605)
Units redeemed		—		—		(572)		—
Long-term incentive performance units		7,885		9,374		23,654		28,932
Contributions by noncontrolling interests, net, and other		47		51		161		287
Noncontrolling interests, end of period	$	513,885	$	557,464	$	513,885	$	557,464

The Operating Partnership

Our evaluation of the appropriateness of classifying the Operating Partnership’s common units of partnership interest, or units, held by Simon and the Operating Partnership's limited partners within permanent equity considered several significant factors. First, as a limited partnership, all decisions relating to the Operating Partnership’s operations and distributions are made by Simon, acting as the Operating Partnership’s sole general partner. The decisions of the general partner are made by Simon's Board of Directors or management. The Operating Partnership has no other governance structure. Secondly, the sole asset of Simon is its interest in the Operating Partnership. As a result, a share of common stock of Simon, or common stock, if owned by the Operating Partnership, is best characterized as being similar to a treasury share and thus not an asset of the Operating Partnership.

Limited partners of the Operating Partnership have the right under the Operating Partnership’s partnership agreement to exchange their units for shares of common stock or cash, as selected by Simon as the sole general partner. Accordingly, we classify units held by limited partners in permanent equity because Simon may elect to issue shares of common stock to limited partners exercising their exchange rights rather than using cash. Under the Operating Partnership’s partnership agreement, the Operating Partnership is required to redeem units held by Simon only when Simon has repurchased shares of common stock. We classify units held by Simon in permanent equity because the decision to redeem those units would be made by Simon.

Net income attributable to noncontrolling interests (which includes nonredeemable and redeemable noncontrolling interests in consolidated properties) is a component of consolidated net income.

A rollforward of noncontrolling interests is as follows:


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling nonredeemable interests in properties, net — beginning of period	$	3,632		4,264	$	3,738	$	5,116
Net income attributable to noncontrolling nonredeemable interests		318		316		1,063		1,388
Distributions to noncontrolling nonredeemable interestholders		(56)		(800)		(1,020)		(2,960)
Contributions by noncontrolling nonredeemable interests, net, and other		48		51		161		287
Noncontrolling nonredeemable interests in properties, net — end of period	$	3,942	$	3,831	$	3,942	$	3,831

Accumulated Other Comprehensive Income (Loss)

Simon

The changes in components of our accumulated other comprehensive income (loss) attributable to common stockholders consisted of the following net of noncontrolling interest as of September 30, 2018:


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(118,138)	$	8,055	$	(370)	$	(110,453)
Other comprehensive (loss) income before reclassifications		(30,853)		17,645		(76)		(13,284)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,144		—		5,144
Net current-period other comprehensive (loss) income		(30,853)		22,789		(76)		(8,140)
Ending balance	$	(148,991)	$	30,844	$	(446)	$	(118,593)

The reclassifications out of accumulated other comprehensive income (loss) consisted of the following during the nine months ended September 30:


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense
		785		955	Net income attributable to noncontrolling interests
	$	(5,144)	$	(6,283)

Realized gain on sale of marketable securities	$	—	$	21,541	Other income
		—		(2,843)	Net income attributable to noncontrolling interests
	$	—	$	18,698

The Operating Partnership

The changes in accumulated other comprehensive income (loss) by component consisted of the following as of September 30, 2018:


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(135,940)	$	9,263	$	(425)	$	(127,102)
Other comprehensive (loss) income before reclassifications		(35,797)		20,355		(88)		(15,530)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,929		—		5,929
Net current-period other comprehensive (loss) income		(35,797)		26,284		(88)		(9,601)
Ending balance	$	(171,737)	$	35,547	$	(513)	$	(136,703)

The reclassifications out of accumulated other comprehensive income (loss) consisted of the following during the nine months ended September 30:


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense

Realized gain on sale of marketable securities	$	—	$	21,541	Other income

Derivative Financial Instruments

We record all derivatives on our consolidated balance sheets at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether we have designated a derivative as a hedge and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. We may use a variety of derivative financial instruments in the normal course of business to selectively manage or hedge a portion of the risks associated with our indebtedness and interest payments. Our objectives in using interest rate derivatives are to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we primarily use interest rate swaps and caps. We require that hedging derivative instruments be highly effective in reducing the risk exposure that they are designated to hedge. We formally designate any instrument that meets these hedging criteria as a hedge at the inception of the derivative contract. We have no credit‑risk‑related hedging or derivative activities.

As of September 30, 2018 and December 31, 2017, we had no outstanding interest rate derivatives. We generally do not apply hedge accounting to interest rate caps, which had a nominal value as of September 30, 2018 and December 31, 2017, respectively.

We are also exposed to fluctuations in foreign exchange rates on financial instruments which are denominated in foreign currencies, primarily in Yen and Euro. We use currency forward contracts, cross currency swap contracts and foreign currency denominated debt to manage our exposure to changes in foreign exchange rates on certain Yen and Euro‑denominated receivables and net investments. Currency forward contracts involve fixing the Yen:USD or Euro:USD exchange rate for delivery of a specified amount of foreign currency on a specified date. The currency forward contracts are typically cash settled in U.S. dollars for their fair value at or close to their settlement date.

We had the following Euro:USD forward contracts designated as net investment hedges at September 30, 2018 and December 31, 2017 (in millions):


			Asset (Liability) Value as of
			September 30,		December 31,
Notional Value		Maturity Date	2018		2017
€	50.0	May 15, 2019		0.4		(2.4)
€	50.0	May 15, 2019		(2.1)		(4.9)
€	50.0	May 15, 2020		(2.9)		(5.2)
€	50.0	May 14, 2021		(3.6)		(5.5)

Asset balances in the above table are included in deferred costs and other assets. Liability balances in the above table are included in other liabilities.

In the first quarter of 2018, we entered into a Euro-denominated cross-currency swap agreement to manage our exposure to changes in foreign exchange rates by swapping $150.0 million of 4.38% fixed rate U.S. dollar-denominated debt to 1.37% fixed rate Euro-denominated debt of €121.6 million. The cross-currency swap matures on December 1, 2020. The fair value of our cross‑currency swap agreement at September 30, 2018 is $8.0 million and is included in deferred costs and other assets. In the third quarter of 2018, we entered into a Yen-denominated cross-currency swap agreement designated as a net investment hedge by swapping $200.1 million of 4.38% fixed rate U.S. dollar-denominated debt to ¥22.3 billion of 1.19% fixed rate Yen-denominated debt. Contemporaneously, we repaid Yen-denominated borrowings of $201.3 million (U.S. dollar equivalent) on the Operating Partnership’s $4.0 billion unsecured revolving credit facility, or Credit Facility. The cross-currency swap matures on December 1, 2020. The fair value of our cross-currency swap agreement at September 30, 2018 is $4.0 million and is included in deferred costs and other assets.

We have designated the currency forward contracts and cross-currency swaps as net investment hedges. Accordingly, we report the changes in fair value in other comprehensive income (loss). Changes in the value of these forward contracts are offset by changes in the underlying hedged Euro or Yen-denominated joint venture investment.

The total gross accumulated other comprehensive income related to the Operating Partnership’s derivative activities, including our share of the other comprehensive income from unconsolidated entities, approximated $35.6 million and $9.3 million as of September 30, 2018 and December 31, 2017, respectively.

New Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014‑09, "Revenue From Contracts With Customers." ASU 2014-09 amends the existing accounting standards for revenue recognition. The new standard provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to their customers. The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain nonfinancial assets, such as property, including real estate.

Our revenues impacted by this standard primarily include management, development, leasing and financing fee revenues for services performed related to various domestic joint ventures that we manage, licensing fees earned from various international properties, sales of real estate, including land parcels and operating properties, and other ancillary income earned at our properties. For the years ended December 31, 2017 and 2016, these revenues were less than 6.0% and 7.0% of consolidated revenue, respectively. The amount and timing of revenue recognition from our services to joint ventures, licensing fee arrangements, and ancillary income under the newly effective standard is consistent with the prior measurement and pattern of recognition. In addition, we do not actively sell operating properties as part of our core business strategy and, accordingly, the sale of properties does not generally constitute a significant part of our revenue and cash flows. We adopted the standard using the modified retrospective approach on January 1, 2018 and there was no cumulative effect adjustment recognized. Our revenues impacted by this standard are included in management fees and other revenues and in other income in the accompanying consolidated statements of operations and comprehensive income.

In January 2016, the FASB issued ASU 2016-01, "Financial Instruments — Overall: Recognition and Measurement of Financial Assets and Financial Liabilities," which requires entities to recognize changes in equity investments with readily determinable fair values in net income. We recognized a cumulative effect adjustment of $7.3 million as of adoption on January 1, 2018 to reclassify unrealized gains previously reported in accumulated other comprehensive income for equity instruments with readily determinable fair values that were previously accounted for as available-for-sale securities and certain equity instruments previously accounted for using the cost method for which the measurement alternative described below was not elected. For those equity instruments that do not have readily determinable fair values, the ASU permits the application of a measurement alternative using the cost of the investment, less any impairments, plus or minus changes resulting from observable price changes for an identical or similar investment of the same issuer. This guidance will be applied prospectively upon the occurrence of an event which establishes fair value to all other equity instruments we account for using the measurement alternative.

In February 2016, the FASB issued ASU 2016-02, "Leases," which will result in lessees recognizing most leased assets and corresponding lease liabilities on the balance sheet. Lessor accounting will remain substantially similar to the current accounting; however, certain refinements were made to conform the standard with the recently issued revenue recognition guidance in ASU 2014-09, specifically related to the allocation and recognition of contract consideration earned from lease and non-lease revenue components. ASU 2016-02 also limits the capitalization of leasing costs to initial direct costs, which will likely result in a reduction to our capitalized leasing costs and an increase in expenses, though the amount of such change is highly dependent upon the leasing compensation structures in place at the time of adoption.

Substantially all of our revenues and the revenues of our equity method investments are earned from arrangements that are within the scope of ASU 2016-02. Upon adoption of ASU 2016-02, consideration related to non-lease components identified in our lease arrangements will be accounted for using the guidance in ASU 2014-09, which we have determined would (i) necessitate that we reallocate consideration received under many of our lease arrangements between the lease and non-lease component, (ii) result in recognizing revenue allocated to our primary non-lease component (consideration received from fixed common area maintenance arrangements) on a straight-line basis and (iii) require separate presentation of revenue recognized from lease and non-lease components on our statements of operations and comprehensive income. However, on July 30, 2018, the FASB issued ASU 2018-11, which created a practical expedient that provides lessors an option not to separate lease and non-lease components when certain criteria are met and instead account for those components as a single component. We believe we meet the criteria to account for lease and non-lease components as a single component, which would alleviate the requirement upon adoption of ASU 2016-02 that we reallocate or separately present lease and non-lease components. We would, however, recognize consideration received from fixed common area maintenance arrangements on a straight-line basis.

Further, upon adoption of ASU 2016-02, leases of land and other arrangements where we are the lessee will be recognized on our balance sheet. Undiscounted future minimum lease payments beginning with the date of adoption due under long-term ground leases with termination dates which range from 2019 to 2090, excluding extension options, over the term of these leases total approximately $782.8 million as of September 30, 2018. The adoption of the guidance will result in the recognition of leased assets and corresponding liabilities discounted over the life of the applicable leases.

We will adopt ASU 2016-02 and any subsequent amendments beginning in the first quarter of 2019. In ASU 2018-11, the FASB also provided a transition option that would permit the application of the new guidance as of the adoption date rather than to all periods presented. We are currently evaluating the impact that the adoption of the new standard and related ASUs will have on our consolidated financial statements and method of adoption.

In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses," which introduces new guidance for an approach based on expected losses to estimate credit losses on certain types of financial instruments. It also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. Instruments in scope include loans, held-to-maturity debt securities, and net investments in leases as well as reinsurance and trade receivables. On August 20, 2018, the FASB issued a proposal that would clarify that operating lease receivables would be outside the scope of the new standard. This standard will be effective for us in fiscal years beginning after December 15, 2019. We are currently evaluating the impact that the adoption of the new standard will have on our consolidated financial statements.

In February 2017, the FASB issued ASU 2017-05, “Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets,” which clarifies the scope and application of Accounting Standards Codification 610-20 on the sale or transfer of nonfinancial assets and in substance assets to noncustomers, including partial sales. The standard generally aligns the measurement of a retained interest in a nonfinancial asset with that of a retained interest in a business. It also eliminates the use of the carryover basis for contributions of real estate into a joint venture where control of the real estate is not retained, which will result in the recognition of a gain or loss upon contribution. We adopted the standard using the modified retrospective approach on January 1, 2018 and there was no cumulative effect adjustment to recognize.

In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities," which introduced amendments to the hedge accounting model to allow for better alignment with risk management practices in addition to simplifying the hedge accounting model. The provisions may permit more risk management strategies to qualify for hedge accounting, including interest rate hedges and foreign currency hedges. We early adopted the ASU on January 1, 2018 as permitted under the standard. There was no impact on our consolidated financial statements at adoption.

Per Share and Per Unit Data

9 Months Ended

Sep. 30, 2018

Per Share and Per Unit Data

Per Share and Per Unit Data

4. Per Share and Per Unit Data

We determine basic earnings per share and basic earnings per unit based on the weighted average number of shares of common stock or units, as applicable, outstanding during the period and we consider any participating securities for purposes of applying the two-class method. We determine diluted earnings per share and diluted earnings per unit based on the weighted average number of shares of common stock or units, as applicable, outstanding combined with the incremental weighted average number of shares or units, as applicable, that would have been outstanding assuming all potentially dilutive securities were converted into shares of common stock or units, as applicable, at the earliest date possible. The following tables set forth the components of basic and diluted earnings per share and basic and diluted earnings per unit.

Simon


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2018		2017		2018		2017
Net Income attributable to Common Stockholders — Basic and Diluted	$	556,267	$	513,783	$	1,723,925	$	1,373,509
Weighted Average Shares Outstanding — Basic and Diluted		309,294,045		310,853,299		309,739,557		311,740,360

For the three and nine months ended September 30, 2018, potentially dilutive securities include units that are exchangeable for common stock and long-term incentive performance units, or LTIP units, granted under our long-term incentive performance programs that are convertible into units and exchangeable for common stock. No securities had a material dilutive effect for the three or nine months ended September 30, 2018 and 2017. We have not adjusted net income attributable to common stockholders and weighted average shares outstanding for income allocable to limited partners or units, respectively, as doing so would have no dilutive impact. We accrue dividends when they are declared.

The Operating Partnership


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2018		2017		2018		2017
Net Income attributable to Unitholders — Basic and Diluted	$	640,402	$	591,872	$	1,984,527	$	1,581,864
Weighted Average Units Outstanding — Basic and Diluted		356,073,080		358,115,572		356,562,262		359,029,893

For the three and nine months ended September 30, 2018, potentially dilutive securities include LTIP units. No securities had a material dilutive effect for the three or nine months ended September 30, 2018 and 2017. We accrue distributions when they are declared.

Investment in Unconsolidated Entities

9 Months Ended

Sep. 30, 2018

Investment in Unconsolidated Entities

Investments in Unconsolidated Entities

5. Investment in Unconsolidated Entities

Real Estate Joint Ventures and Investments

Joint ventures are common in the real estate industry. We use joint ventures to finance properties, develop new properties and diversify our risk in a particular property or portfolio of properties. As discussed in Note 2, we held joint venture interests in 81 properties as of September 30, 2018.

Certain of our joint venture properties are subject to various rights of first refusal, buy‑sell provisions, put and call rights, or other sale or marketing rights for partners which are customary in real estate joint venture agreements and the industry. We and our partners in these joint ventures may initiate these provisions (subject to any applicable lock up or similar restrictions), which may result in either the sale of our interest or the use of available cash or borrowings, or the use of limited partnership interests in the Operating Partnership, to acquire the joint venture interest from our partner.

We may provide financing to joint ventures primarily in the form of interest bearing construction loans. As of September 30, 2018 and December 31, 2017, we had construction loans and other advances to related parties totaling $86.0 million and $87.0 million, respectively, which are included in deferred costs and other assets in the accompanying consolidated balance sheets.

Unconsolidated Entity Transactions

On September 25, 2018, as discussed in Note 9, we acquired the remaining 50% interest in The Outlets at Orange from our joint venture partner. The Operating Partnership issued 475,183 units at a price of $176.99 to acquire this remaining interest. As a result of this acquisition, we now own 100% of this property.

On September 11, 2018, we announced a joint venture with Macerich to co-develop, co-own, and jointly lease the approximately 400,000 square foot Los Angeles Premium Outlets, followed by a proposed phase II of an additional 166,000 square feet. As of September 30, 2018, we had contributed $13.1 million to the venture. We own a 50% noncontrolling interest in this project, which is scheduled to open in the fall of 2021.

On June 7, 2018, Aventura Mall, a property in which we own a 33.3% interest, refinanced its $1.2 billion mortgage and its $200.8 million construction loan with a $1.75 billion mortgage at a fixed interest rate of 4.12% that matures on July 1, 2028. An early repayment charge of $30.9 million was incurred at the property, which along with the write-off of deferred debt issuance costs of $6.5 million, is included in interest expense in the accompanying combined joint venture statements of operations. Our $12.5 million share of the charge associated with the repayment is included in income from unconsolidated entities in the accompanying consolidated statements of operations and comprehensive income. Excess proceeds from the financing were distributed to the venture partners in June 2018.

In May 2017, Colorado Mills, a property in which we have a 37.5% interest, sustained significant hail damage. During the second quarter of 2017, the property recorded an impairment charge of approximately $32.5 million based on the net carrying value of the assets damaged, which was fully offset by anticipated insurance recoveries. As of September 30, 2018, the property had received business interruption proceeds and also property damage proceeds of $58.3 million, which resulted in the property recording a $25.8 million gain in 2018. Our share of the gain, $9.7 million, is reflected within the gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net in the accompanying consolidated statements of operations and comprehensive income.

On September 15, 2016, we and a group of co-investors acquired certain assets and liabilities of Aéropostale, a retailer of apparel and accessories, out of bankruptcy. The interests were acquired through two separate joint ventures, a licensing venture and an operating venture. In April 2018, we contributed our entire interest in the licensing venture in exchange for additional interests in ABG, a brand development, marketing, and entertainment company. As a result, we recognized a $35.6 million non‑cash gain representing the increase in value of our previously held interest in the licensing venture, which is included in other income in the accompanying consolidated statements of operations and comprehensive income. At September 30, 2018, our noncontrolling equity method interests in the operations venture of Aéropostale and in ABG were 44.95% and 5.78%, respectively.

As of September 30, 2018 and December 31, 2017, we had an 11.7% noncontrolling equity interest in HBS, a joint venture we formed with Hudson’s Bay Company. HBS has 42 properties in the U.S. and, subsequent to formation, acquired 41 properties from Kaufhof. As of September 30, 2018, we had contributed $68.3 million for improvements to certain properties. In addition, we contributed $178.5 million in connection with the HBS acquisition of the Kaufhof department stores. On September 11, 2018, Hudson’s Bay Company announced that HBS intends to sell its interest in the Kaufhof department stores to Hudson’s Bay Company and SIGNA Retail Holdings. HBS will retain its ownership in the properties in the U.S. and we will continue to hold an 11.7% noncontrolling interest in the remaining HBS joint venture subsequent to the closing of the transaction, which is expected to occur in the fourth quarter of 2018. Our share of net income, net of amortization of our excess investment, was $4.3 million and $4.8 million for the three months ended September 30, 2018 and 2017, respectively, and $11.9 million and $11.3 million for the nine months ended September 30, 2018 and 2017, respectively. Total revenues, operating income and consolidated net income were approximately $258.8 million, $162.2 million and $90.6 million, respectively, for the nine months ended September 30, 2018 and $265.8 million, $246.9 million and $176.2 million, respectively, for the nine months ended September 30, 2017.

European Investments

At September 30, 2018, we owned 63,924,148 shares, or approximately 21.2%, of Klépierre, which had a quoted market price of $35.43 per share. Our share of net income, net of amortization of our excess investment, was $22.4 million and $14.1 million for the three months ended September 30, 2018 and 2017, respectively, and $70.0 million and $37.2 million for the nine months ended September 30, 2018 and 2017, respectively. Based on applicable Euro:USD exchange rates and after our conversion of Klépierre’s results to GAAP, Klépierre’s total revenues, operating income and consolidated net income were approximately $1.2 billion, $496.4 million and $485.8 million, respectively, for the nine months ended September 30, 2018 and $1.1 billion, $406.3 million and $298.3 million, respectively, for the nine months ended September 30, 2017.

During the nine months ended September 30, 2018 and September 30, 2017, Klépierre completed the disposal of its interests in certain shopping centers. In connection with these disposals, we recorded a gain of $13.4 million and $5.0 million, respectively, representing our share of the gains recognized by Klépierre, which is included in gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net in the accompanying consolidated statements of operations and comprehensive income.

We have an interest in a European investee that had interests in nine Designer Outlet properties as of September 30, 2018 and December 31, 2017, respectively. As of September 30, 2018, our legal percentage ownership interests in these properties ranged from 45% to 94%.

In addition, we have a 50.0% noncontrolling interest in a European property management and development company that provides services to the Designer Outlet properties.

We also have minority interests in Value Retail PLC and affiliated entities, which own or have interests in and operate nine luxury outlets located throughout Europe and we have a direct minority ownership in three of those outlets. At September 30, 2018 and December 31, 2017, the carrying value of these equity instruments was $140.8 million and is included in deferred costs and other assets.

Asian Joint Ventures

We conduct our international Premium Outlet operations in Japan through a joint venture with Mitsubishi Estate Co., Ltd. We have a 40% noncontrolling ownership interest in this joint venture. The carrying amount of our investment in this joint venture was $221.2 million and $230.3 million as of September 30, 2018 and December 31, 2017, respectively, including all related components of accumulated other comprehensive income (loss). We conduct our international Premium Outlet operations in South Korea through a joint venture with Shinsegae International Co. We have a 50% noncontrolling ownership interest in this joint venture. The carrying amount of our investment in this joint venture was $159.8 million and $149.1 million as of September 30, 2018 and December 31, 2017, respectively, including all related components of accumulated other comprehensive income (loss).

Summary Financial Information

A summary of our equity method investments and share of income from such investments, excluding Klépierre, and our investments in Aéropostale, ABG and HBS follows.

COMBINED BALANCE SHEETS


	September 30,		December 31,
	2018		2017
Assets:
Investment properties, at cost	$	18,632,287	$	18,328,747
Less - accumulated depreciation		6,672,267		6,371,363
		11,960,020		11,957,384
Cash and cash equivalents		1,013,153		956,084
Tenant receivables and accrued revenue, net		403,315		403,125
Deferred costs and other assets		395,144		355,585
Total assets	$	13,771,632	$	13,672,178
Liabilities and Partners’ Deficit:
Mortgages	$	15,231,476	$	14,784,310
Accounts payable, accrued expenses, intangibles, and deferred revenue		903,599		1,033,674
Other liabilities		351,116		365,857
Total liabilities		16,486,191		16,183,841
Preferred units		67,450		67,450
Partners’ deficit		(2,782,009)		(2,579,113)
Total liabilities and partners’ deficit	$	13,771,632	$	13,672,178
Our Share of:
Partners’ deficit	$	(1,204,237)	$	(1,144,620)
Add: Excess Investment		1,614,277		1,733,063
Our net Investment in unconsolidated entities, at equity	$	410,040	$	588,443

“Excess Investment” represents the unamortized difference of our investment over our share of the equity in the underlying net assets of the joint ventures or other investments acquired and is allocated on a fair value basis primarily to investment properties, lease related intangibles, and debt premiums and discounts. We amortize excess investment over the life of the related depreciable components of investment properties, typically no greater than 40 years, the terms of the applicable leases and the applicable debt maturity, respectively. The amortization is included in the reported amount of income from unconsolidated entities.

COMBINED STATEMENTS OF OPERATIONS


	For The Three				For The Nine
	Months Ended				Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
REVENUE:
Minimum rent	$	483,685	$	466,601	$	1,443,617	$	1,383,361
Overage rent		52,417		52,560		163,144		150,376
Tenant reimbursements		222,153		215,774		666,068		644,020
Other income		73,259		74,208		232,747		210,287
Total revenue		831,514		809,143		2,505,576		2,388,044
OPERATING EXPENSES:
Property operating		151,873		145,288		437,718		410,301
Depreciation and amortization		161,964		156,682		488,098		469,884
Real estate taxes		60,654		54,668		197,497		185,228
Repairs and maintenance		20,035		18,811		63,968		59,512
Advertising and promotion		20,318		19,837		65,425		63,871
Provision for credit losses		1,300		1,063		13,378		7,629
Other		43,916		45,174		143,533		133,558
Total operating expenses		460,060		441,523		1,409,617		1,329,983
Operating Income		371,454		367,620		1,095,959		1,058,061
Interest expense		(163,855)		(149,746)		(505,540)		(438,393)
Gain on sale or disposal of, or recovery on, assets and interests in unconsolidated entities, net		—		—		25,792		—
Net Income	$	207,599	$	217,874	$	616,211	$	619,668
Third-Party Investors’ Share of Net Income	$	101,750	$	110,581	$	304,174	$	314,531
Our Share of Net Income		105,849		107,293		312,037		305,137
Amortization of Excess Investment		(21,526)		(22,608)		(64,447)		(68,045)
Our Share of Gain on Sale or Disposal of, or Recovery on, Assets and Interests in Unconsolidated Entities, net		—		—		(9,672)		—
Income from Unconsolidated Entities	$	84,323	$	84,685	$	237,918	$	237,092

Our share of income from unconsolidated entities in the above table, aggregated with our share of the results of Klépierre, and our investments in Aéropostale, ABG and HBS, is presented in income from unconsolidated entities in the accompanying consolidated statements of operations and comprehensive income. Unless otherwise noted, our share of the gain on sale or disposal of, or recovery on, assets and interests in unconsolidated entities, net is reflected within gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net in the accompanying consolidated statements of operations and comprehensive income.

Debt

9 Months Ended

Sep. 30, 2018

Debt

Debt

6. Debt

Unsecured Debt

At September 30, 2018, our unsecured debt consisted of $15.7 billion of senior unsecured notes of the Operating Partnership, $125.0 million outstanding under the Credit Facility, and $996.9 million outstanding under the Operating Partnership’s global unsecured commercial paper note program, or Commercial Paper program.

On September 30, 2018, we had an aggregate available borrowing capacity of $6.4 billion under the Credit Facility and the Operating Partnership’s $3.5 billion unsecured revolving credit facility, or Supplemental Facility, and together with the Credit Facility, the Credit Facilities. The maximum aggregate outstanding balance under the Credit Facilities during the nine months ended September 30, 2018 was $423.1 million and the weighted average outstanding balance was $276.2 million. Letters of credit of $11.6 million were outstanding under the Credit Facilities as of September 30, 2018.

The Credit Facility’s initial borrowing capacity of $4.0 billion may be increased to $5.0 billion during its term and provides for borrowings denominated in U.S. dollars, Euro, Yen, Sterling, Canadian dollars and Australian dollars. Borrowings in currencies other than the U.S. dollar are limited to 95% of the maximum revolving credit amount, as defined. The initial maturity date of the Credit Facility is June 30, 2021 and can be extended for an additional year to June 30, 2022 at our sole option, subject to our continued compliance with the terms thereof. The base interest rate on the Credit Facility is LIBOR plus 77.5 basis points with a facility fee of 10 basis points.

On February 15, 2018, the Operating Partnership amended and extended the Supplemental Facility. The Supplemental Facility’s initial borrowing capacity of $3.5 billion may be increased to $4.5 billion during its term and provides for borrowings denominated in U.S. dollars, Euro, Yen, Sterling, Canadian dollars and Australian dollars. The initial maturity date of the Supplemental Facility was extended to June 30, 2022 and can be extended for an additional year to June 30, 2023 at our sole option, subject to our continued compliance with the terms thereof. The base interest rate on the Supplemental Facility was reduced to LIBOR plus 77.5 basis points from LIBOR plus 80 basis points, with a facility fee of 10 basis points.

The Operating Partnership also has available a Commercial Paper program of $1.0 billion, or the non-U.S. dollar equivalent thereof. The Operating Partnership may issue unsecured commercial paper notes, denominated in U.S. dollars, Euro and other currencies. Notes issued in non-U.S. currencies may be issued by one or more subsidiaries of the Operating Partnership and are guaranteed by the Operating Partnership. Notes will be sold under customary terms in the U.S. and Euro commercial paper note markets and rank (either by themselves or as a result of the guarantee described above) pari passu with the Operating Partnership’s other unsecured senior indebtedness. The Commercial Paper program is supported by the Credit Facilities and if necessary or appropriate, we may make one or more draws under either of the Credit Facilities to pay amounts outstanding from time to time on the Commercial Paper program. On September 30, 2018, we had $996.9 million outstanding under the Commercial Paper program, fully comprised of U.S. dollar-denominated notes with a weighted average interest rate of 2.16%. These borrowings have a weighted average maturity date of December 3, 2018 and reduce amounts otherwise available under the Credit Facilities.

On January 3, 2018, the Operating Partnership redeemed at par $750.0 million of senior unsecured notes with a fixed interest rate of 1.50%.

On July 10, 2018, the Operating Partnership repaid Yen-denominated borrowings of $201.3 million (U.S. dollar equivalent) on the Credit Facility.

Mortgage Debt

Total mortgage indebtedness was $7.0 billion and $6.9 billion at September 30, 2018 and December 31, 2017, respectively.

During the nine months ended September 30, 2018, we repaid a mortgage loan of $86.6 million with an interest rate of 7.79%, unencumbering the property.

On July 30, 2018, Noventa di Piave Designer Outlet, in which we own a 90% interest, refinanced its €110.0 million, 1.68% variable rate mortgage maturing in 2020 with a €260.0 million, 2.00% fixed rate mortgage that matures in 2025.

On September 25, 2018, as discussed in Note 9, we acquired the remaining 50% interest in The Outlets at Orange from our joint venture partner, resulting in the consolidation of the existing fixed rate mortgage of $215.0 million. The loan matures on April 1, 2024 and bears interest at 4.22%.

Covenants

Our unsecured debt agreements contain financial covenants and other non-financial covenants. If we were to fail to comply with these covenants, after the expiration of the applicable cure periods, the debt maturity could be accelerated or other remedies could be sought by the lender, including adjustments to the applicable interest rate. As of September 30, 2018, we were in compliance with all covenants of our unsecured debt.

At September 30, 2018, we or our subsidiaries were the borrowers under 46 non‑recourse mortgage notes secured by mortgages on 49 properties, including two separate pools of cross‑defaulted and cross‑collateralized mortgages encumbering a total of five properties. Under these cross‑default provisions, a default under any mortgage included in the cross‑defaulted pool may constitute a default under all mortgages within that pool and may lead to acceleration of the indebtedness due on each property within the pool. Certain of our secured debt instruments contain financial and other non‑financial covenants which are specific to the properties that serve as collateral for that debt. If the applicable borrower under these non-recourse mortgage notes were to fail to comply with these covenants, the lender could accelerate the debt and enforce its rights against their collateral. At September 30, 2018, the applicable borrowers under these non‑recourse mortgage notes were in compliance with all covenants where non‑compliance could individually or in the aggregate, giving effect to applicable cross‑default provisions, have a material adverse effect on our financial condition, liquidity or results of operations.

Fair Value of Debt

The carrying value of our variable‑rate mortgages and other loans approximates their fair values. We estimate the fair values of consolidated fixed rate mortgages using cash flows discounted at current borrowing rates and other indebtedness using cash flows discounted at current market rates. We estimate the fair values of consolidated fixed rate unsecured notes using quoted market prices, or, if no quoted market prices are available, we use quoted market prices for securities with similar terms and maturities. The book value of our consolidated fixed rate mortgages and unsecured indebtedness including commercial paper was $22.8 billion and $23.4 billion as of September 30, 2018 and December 31, 2017, respectively. The fair values of these financial instruments and the related discount rate assumptions as of September 30, 2018 and December 31, 2017 are summarized as follows:


	September 30,			December 31,
	2018			2017
Fair value of fixed rate mortgages and unsecured indebtedness	$	22,554		$	24,003
Weighted average discount rates assumed in calculation of fair value for fixed rate mortgages		4.96	%		4.25	%
Weighted average discount rates assumed in calculation of fair value for unsecured indebtedness		4.80	%		4.10	%

Equity

9 Months Ended

Sep. 30, 2018

Equity

Equity

7. Equity

During the nine months ended September 30, 2018, Simon issued 92,732 shares of common stock to two limited partners of the Operating Partnership in exchange for an equal number of units pursuant to the partnership agreement of the Operating Partnership. During the nine months ended September 30, 2018, the Operating Partnership redeemed 49,219 units from four limited partners for $7.6 million. These transactions increased Simon’s ownership interest in the Operating Partnership.

On September 25, 2018, the Operating Partnership issued 475,183 units in connection with the acquisition of the remaining 50% interest in The Outlets at Orange, as discussed in Note 9.

On February 13, 2017, Simon’s Board of Directors authorized a two-year extension of the previously authorized $2.0 billion common stock repurchase plan through March 31, 2019. Simon may repurchase the shares in the open market or in privately negotiated transactions as market conditions warrant. During the nine months ended September 30, 2018, Simon purchased 1,988,247 shares at an average price of $154.56 per share as part of this program. During the nine months ended September 30, 2017, Simon purchased 2,399,051 shares at an average price of $165.14 per share as part of this program. As Simon repurchases shares under this program, the Operating Partnership repurchases an equal number of units from Simon.

We paid a common stock dividend of $2.00 per share in the third quarter of 2018 and $5.90 per share for the nine months ended September 30, 2018. The Operating Partnership paid distributions per unit for the same amounts. We paid dividends of $1.80 and $5.30 per share for the three and nine months ended September 30, 2017, respectively. The Operating Partnership paid distributions per unit for the same amounts. Simon’s Board of Directors declared a quarterly cash dividend for the fourth quarter of 2018 of $2.00 per share of common stock payable on November 30, 2018 to stockholders of record on November 16, 2018. The distribution rate on units is equal to the dividend rate on common stock.

Temporary Equity

Simon

Simon classifies as temporary equity those securities for which there is the possibility that Simon could be required to redeem the security for cash irrespective of the probability of such a possibility. As a result, Simon classifies one series of preferred units in the Operating Partnership and noncontrolling redeemable interests in properties in temporary equity. Each of these securities is discussed further below.

Limited Partners’ Preferred Interest in the Operating Partnership and Noncontrolling Redeemable Interests in Properties. The redemption features of the preferred units in the Operating Partnership contain provisions which could require the Operating Partnership to settle the redemption in cash. As a result, this series of preferred units in the Operating Partnership remains classified outside permanent equity. The remaining interests in a property or portfolio of properties which are redeemable at the option of the holder or in circumstances that may be outside Simon’s control are accounted for as temporary equity. The carrying amount of the noncontrolling interest is adjusted to the redemption amount assuming the instrument is redeemable at the balance sheet date. Changes in the redemption value of the underlying noncontrolling interest are recorded within accumulated deficit. There were no noncontrolling interests redeemable at amounts in excess of fair value as of September 30, 2018 and December 31, 2017. The following table summarizes the preferred units in the Operating Partnership and the amount of the noncontrolling redeemable interests in properties as follows:


	As of		As of
	September 30,		December 31,
	2018		2017
7.50% Cumulative Redeemable Preferred Units, 260,000 units authorized, 255,373 issued and outstanding	$	25,537	$	25,537
Other noncontrolling redeemable interests in properties		172,400		164,943
Limited partners’ preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties	$	197,937	$	190,480

The Operating Partnership

The Operating Partnership classifies as temporary equity those securities for which there is the possibility that the Operating Partnership could be required to redeem the security for cash, irrespective of the probability of such a possibility. As a result, the Operating Partnership classifies one series of preferred units and noncontrolling redeemable interests in properties in temporary equity. The following table summarizes the preferred units and the amount of the noncontrolling redeemable interests in properties as follows:


	As of		As of
	September 30,		December 31,
	2018		2017
7.50% Cumulative Redeemable Preferred Units, 260,000 units authorized, 255,373 issued and outstanding	$	25,537	$	25,537
Other noncontrolling redeemable interests in properties		172,400		164,943
Total preferred units, at liquidation value, and noncontrolling redeemable interests in properties	$	197,937	$	190,480

Stock Based Compensation

Awards under our stock based compensation plans primarily take the form of LTIP unit and restricted stock grants. Restricted stock and awards under the LTIP programs are all performance based and are based on various individual, corporate and business unit performance measures as further described below. The expense related to these programs, net of amounts capitalized, is included within home and regional office costs and general and administrative costs in the accompanying statements of operations and comprehensive income.

LTIP Programs. The Compensation Committee has approved long‑term, performance based incentive compensation programs, or the LTIP programs, for certain senior executive officers. Awards under the LTIP programs take the form of LTIP units, a form of limited partnership interest issued by the Operating Partnership, which are subject to the participant maintaining employment with us through certain dates and other conditions as described in the applicable award agreements. Awarded LTIP units not earned in accordance with the conditions set forth in the applicable award agreements are forfeited. Earned and fully vested LTIP units are equivalent to units of the Operating Partnership. During the performance period, participants are entitled to receive distributions on the LTIP units awarded to them equal to 10% of the regular quarterly distributions paid on a unit of the Operating Partnership. As a result, we account for these LTIP units as participating securities under the two‑class method of computing earnings per share.

Awards under the LTIP programs for 2016 will be considered earned if, and only to the extent to which, applicable total shareholder return, or TSR, performance measures, as defined in the applicable award agreements, are achieved during the applicable performance periods. Once earned, LTIP units are subject to a two-year vesting period. One‑half of the earned LTIP units will vest on January 1 of each of the second and third years following the end of the applicable performance period.

In 2018, the Compensation Committee established and granted awards under a redesigned LTIP program, or the 2018 LTIP program. Awards under the 2018 LTIP program were granted in two tranches, Tranche A LTIP units and Tranche B LTIP units. Each of the Tranche A LTIP units and the Tranche B LTIP units will be considered earned if, and only to the extent to which, the respective goals based on Funds From Operations, or FFO, per share or Relative TSR Goal performance criteria, as defined in the applicable award agreements, are achieved during the applicable two-year and three-year performance periods of the Tranche A LTIP units and Tranche B LTIP units, respectively. One‑half of the earned Tranche A LTIP units will vest on January 1, 2021 with the other one-half vesting on January 1, 2022. All of the earned Tranche B LTIP units will vest on January 1, 2022.

The grant date fair value of the portion of the LTIP units based on achieving the target FFO performance criteria is $6.25 million for the Tranche A LTIP units and the Tranche B LTIP units, for a total of $12.5 million. The 2018 LTIP program provides that the value of the FFO-based award may be adjusted up or down based on the Company’s performance compared to the target FFO performance criteria and has a maximum potential fair value of $18.75 million. The value of the FFO-based award is recorded as expense over the period from the grant date to the date at which the awards, if earned, would become vested, based on our assessment as to whether it is probable that the performance criteria will be achieved during the applicable performance periods.

The grant date fair values of any LTIP units based on TSR performance are estimated using a Monte Carlo model, and the resulting fixed expense is recorded regardless of whether the TSR performance criteria are achieved if the required service is delivered. The grant date fair values are being amortized into expense over the period from the grant date to the date at which the awards, if earned, would become vested.

The Compensation Committee approved LTIP unit grants as shown in the table below. The extent to which LTIP units were earned, and the aggregate grant date fair value, are as follows:


LTIP Program	LTIP Units Earned	Grant Date Fair Value of TSR Award	Grant Date Target Value of FFO-Based Award
2013-2015 LTIP program	466,405	$28.5 million	—
2014-2016 LTIP program	120,314	$27.5 million	—
2015-2017 LTIP program	—	$25.1 million	—
2016-2018 LTIP program	To be determined in 2019	$26.3 million	—
2018 LTIP program - Tranche A	To be determined in 2020	$6.25 million	$6.25 million
2018 LTIP program - Tranche B	To be determined in 2021	$6.25 million	$6.25 million

We recorded compensation expense, net of capitalization, related to these LTIP programs of approximately $13.0 million and $9.7 million for the nine months ended September 30, 2018 and 2017, respectively.

Restricted Stock. The Compensation Committee awarded 43,043 shares of restricted stock to employees during the nine months ended September 30, 2018 at a weighted-average fair market value of $154.35 per share. During the nine months ended September 30, 2018, our non-employee Directors were awarded an aggregate of 12,648 shares of restricted stock at a weighted average fair market value of $158.71 per share. These shares represent a portion of the compensation we pay our non-employee Directors, and all of the shares have been placed in a non-employee Director deferred compensation account maintained by us. The grant date fair value of the employee restricted stock awards is being recognized as expense over the three-year vesting service period. The grant date fair value of the non-employee Director restricted stock awards is being recognized as expense over the one-year vesting service period. In accordance with the Operating Partnership's partnership agreement, the Operating Partnership issued an equal number of units to Simon that are subject to the same vesting conditions as the restricted stock.

We recorded compensation expense, net of capitalization, related to restricted stock of approximately $6.0 million and $7.6 million for the nine months ended September 30, 2018 and 2017, respectively.

Other Compensation Arrangements. On July 6, 2011, in connection with the execution of an employment agreement, the Compensation Committee granted David Simon, Simon’s Chairman and Chief Executive Officer, a retention award in the form of 1,000,000 LTIP units, or the Award, for his continued service as Simon’s Chairman and Chief Executive Officer through July 5, 2019. Effective December 31, 2013, the Award was modified, or the Current Award, and as a result the LTIP units now become earned and eligible to vest based on the attainment of Company‑based performance goals, in addition to the service‑based vesting requirement included in the original Award. The Current Award does not contain an opportunity for Mr. Simon to receive additional LTIP units above and beyond the original Award should our performance exceed the higher end of the performance criteria. The performance criteria of the Current Award are based on the attainment of specific FFO per share. Because the performance criteria has been met, a maximum of 360,000 LTIP units, or the A units, 360,000 LTIP units, or the B units, and 280,000 LTIP units, or the C units, became earned on December 31, 2015, December 31, 2016 and December 31, 2017, respectively. Based on the Company’s performance in 2015, 360,000 A units were earned. Based on the Company’s performance in 2016, 360,000 B units were earned. Based on the Company’s performance in 2017, 280,000 C units were earned. If the relevant performance criteria had not been achieved, all or a portion of the Current Award would have been forfeited. The earned A units vested on January 1, 2018, earned B units will vest on January 1, 2019 and earned C units will vest on June 30, 2019, subject to Mr. Simon’s continued employment through such applicable date. The grant date fair value of the retention award of $120.3 million is being recognized as expense over the eight‑year term of his employment agreement on a straight‑line basis based through the applicable vesting periods of the A units, B units and C units.

Changes in Equity

Simon

The following table provides a reconciliation of the beginning and ending carrying amounts of total equity, equity attributable to common stockholders and equity attributable to noncontrolling interests:


					Accumulated						Common
					Other		Capital in				Stock
	Preferred		Common		Comprehensive		Excess of		Accumulated		Held in		Noncontrolling		Total
	Stock		Stock		Income (Loss)		Par Value		Deficit		Treasury		interests		Equity
January 1, 2018	$	43,077	$	32	$	(110,453)	$	9,614,748	$	(4,782,173)	$	(1,079,063)	$	552,596	$	4,238,764
Exchange of limited partner units for common shares								1,004						(1,004)		—
Issuance of limited partner units														84,103		84,103
Treasury stock purchase												(307,296)				(307,296)
Redemption of limited partner units								(7,047)						(572)		(7,619)
LTIP units														23,654		23,654
Cumulative effect of accounting change										7,264						7,264
Purchase and disposition of noncontrolling interests, net and other		(247)						308		(18,663)		5,740		161		(12,701)
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership								127,707						(127,707)		—
Distributions to common stockholders and limited partners, excluding Operating Partnership preferred interests										(1,829,610)				(276,530)		(2,106,140)
Distributions to other noncontrolling interest partners														(1,020)		(1,020)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties						(8,140)				1,726,428				260,204		1,978,492
September 30, 2018	$	42,830	$	32	$	(118,593)	$	9,736,720	$	(4,896,754)	$	(1,380,619)	$	513,885	$	3,897,501

The Operating Partnership

The following table provides a reconciliation of the beginning and ending carrying amounts of total equity, equity attributable to partners and equity attributable to noncontrolling interests:


	Preferred		Simon (Managing		Limited		Noncontrolling		Total
	Units		General Partner)		Partners		interests		Equity
January 1, 2018	$	43,077	$	3,643,091	$	548,858	$	3,738	$	4,238,764
Issuance of limited partner units						84,103				84,103
Limited partner units exchanged to units				1,004		(1,004)				—
Treasury unit purchase				(307,296)						(307,296)
Redemption of limited partner units				(7,047)		(572)				(7,619)
LTIP Units						23,654				23,654
Cumulative effect of accounting change				7,264						7,264
Purchase and disposition of noncontrolling interests, net and other		(247)		(12,615)				161		(12,701)
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership				127,707		(127,707)				—
Distributions to limited partners, excluding preferred interests classified as temporary equity		(2,503)		(1,827,107)		(276,530)		(1,020)		(2,107,160)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties		2,503		1,715,785		259,141		1,063		1,978,492
September 30, 2018	$	42,830	$	3,340,786	$	509,943	$	3,942	$	3,897,501

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2018
Commitments and Contingencies.
Commitments and Contingencies	8. Commitments and Contingencies Litigation We are involved from time-to-time in various legal and regulatory proceedings that arise in the ordinary course of our business, including, but not limited to, commercial disputes, environmental matters, and litigation in connection with transactions such as acquisitions and divestitures. We believe that current proceedings will not have a material adverse effect on our financial condition, liquidity, or results of operations. We record a liability when a loss is considered probable and the amount can be reasonably estimated. Guarantees of Indebtedness Joint venture debt is the liability of the joint venture and is typically secured by the joint venture property, which is non‑recourse to us. As of September 30, 2018 and December 31, 2017, the Operating Partnership guaranteed joint venture related mortgage indebtedness of $215.5 million and $211.6 million, respectively (of which we have a right of recovery from our venture partners of $10.8 million). Mortgages guaranteed by the Operating Partnership are secured by the property of the joint venture which could be sold in order to satisfy the outstanding obligation and which has an estimated fair value in excess of the guaranteed amount. Concentration of Credit Risk Our U.S. Malls, Premium Outlets, and The Mills rely heavily upon anchor tenants to attract customers; however, anchor retailers do not contribute materially to our financial results as many anchor retailers own their spaces. All material operations are within the United States and no customer or tenant accounts for 5% or more of our consolidated revenues. Hurricane Impacts During the third quarter of 2017, two of our wholly-owned properties located in Puerto Rico sustained significant damage as a result of Hurricane Maria. Due to the conditions on the island, we were unable to determine a reliable estimate or a range of reliable estimates of the extent of the damages at these properties at the end of the third quarter of 2017. During the fourth quarter of 2017, as additional information became available, we recorded an impairment of approximately $19.0 million related to damages at these properties, which was offset by an insurance recovery receivable. During the nine months ended September 30, 2018, we received $50.3 million of insurance proceeds related to the two properties located in Puerto Rico, of which $33.3 million was used for property restoration and remediation and to reduce the insurance recovery receivable, and $17.0 million was recorded as business interruption proceeds and is included in other income in the accompanying consolidated statements of operations and comprehensive income.

Real Estate Acquisitions and Dispositions	9 Months Ended
Real Estate Acquisitions and Dispositions	Sep. 30, 2018
Real Estate Acquisitions and Dispositions
Real Estate Acquisitions and Dispositions	9. Real Estate Acquisitions and Dispositions During the first nine months of 2018, we recorded net gains of $144.9 million primarily related to disposition activity which included the foreclosure of a consolidated property in satisfaction of its $200 million non-recourse mortgage. Unless otherwise noted, gains and losses on the above are included in gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net in the accompanying consolidated statements of operations and comprehensive income. We capitalize asset acquisition costs and expense costs related to business combinations, as well as disposition related costs as they are incurred. We incurred a minimal amount of transaction expenses during the nine months ended September 30, 2018 and 2017. On September 25, 2018, we acquired the remaining 50% interest in The Outlets at Orange from our joint venture partner. The Operating Partnership issued 475,183 units, or approximately $84.1 million, as consideration for the acquisition. The property is subject to a $215.0 million 4.22% fixed rate mortgage. We accounted for this transaction as an asset acquisition and substantially all of our investment has been determined to relate to investment property.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

Significant Accounting Policies

Cash and Cash Equivalents

Equity Instruments and Debt Securities

Our captive insurance subsidiary is required to maintain statutory minimum capital and surplus as well as maintain a minimum liquidity ratio. Therefore, our access to these securities may be limited.

Fair Value Measurements

Noncontrolling Interests

Simon

Details of the carrying amount of our noncontrolling interests are as follows:


	As of		As of
	September 30,		December 31,
	2018		2017
Limited partners’ interests in the Operating Partnership	$	509,943	$	548,858
Nonredeemable noncontrolling interests in properties, net		3,942		3,738
Total noncontrolling interests reflected in equity	$	513,885	$	552,596

A rollforward of noncontrolling interests is as follows:


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling interests, beginning of period	$	507,604		564,444	$	552,596	$	649,464
Net income attributable to noncontrolling interests after preferred distributions and income attributable to redeemable noncontrolling interests in consolidated properties		84,452		78,405		261,665		209,743
Distributions to noncontrolling interest holders		(93,637)		(86,125)		(277,550)		(254,026)
Other comprehensive (loss) income allocable to noncontrolling interests:
Unrealized gain (loss) on derivative hedge agreements		717		(1,135)		2,710		(4,116)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings		214		(2,555)		785		(1,887)
Currency translation adjustments		(1,573)		1,712		(4,944)		5,511
Changes in available-for-sale securities and other		(3)		895		(12)		846
		(645)		(1,083)		(1,461)		354
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership		(74,990)		(7,350)		(127,707)		(75,685)
Units issued to limited partners		84,103		—		84,103		—
Units exchanged for common shares		(934)		(252)		(1,004)		(1,605)
Units redeemed		—		—		(572)		—
Long-term incentive performance units		7,885		9,374		23,654		28,932
Contributions by noncontrolling interests, net, and other		47		51		161		287
Noncontrolling interests, end of period	$	513,885	$	557,464	$	513,885	$	557,464

The Operating Partnership

Net income attributable to noncontrolling interests (which includes nonredeemable and redeemable noncontrolling interests in consolidated properties) is a component of consolidated net income.

A rollforward of noncontrolling interests is as follows:


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling nonredeemable interests in properties, net — beginning of period	$	3,632		4,264	$	3,738	$	5,116
Net income attributable to noncontrolling nonredeemable interests		318		316		1,063		1,388
Distributions to noncontrolling nonredeemable interestholders		(56)		(800)		(1,020)		(2,960)
Contributions by noncontrolling nonredeemable interests, net, and other		48		51		161		287
Noncontrolling nonredeemable interests in properties, net — end of period	$	3,942	$	3,831	$	3,942	$	3,831

Accumulated Other Comprehensive Income (Loss)

Simon

The changes in components of our accumulated other comprehensive income (loss) attributable to common stockholders consisted of the following net of noncontrolling interest as of September 30, 2018:


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(118,138)	$	8,055	$	(370)	$	(110,453)
Other comprehensive (loss) income before reclassifications		(30,853)		17,645		(76)		(13,284)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,144		—		5,144
Net current-period other comprehensive (loss) income		(30,853)		22,789		(76)		(8,140)
Ending balance	$	(148,991)	$	30,844	$	(446)	$	(118,593)

The reclassifications out of accumulated other comprehensive income (loss) consisted of the following during the nine months ended September 30:


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense
		785		955	Net income attributable to noncontrolling interests
	$	(5,144)	$	(6,283)

Realized gain on sale of marketable securities	$	—	$	21,541	Other income
		—		(2,843)	Net income attributable to noncontrolling interests
	$	—	$	18,698

The Operating Partnership

The changes in accumulated other comprehensive income (loss) by component consisted of the following as of September 30, 2018:


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(135,940)	$	9,263	$	(425)	$	(127,102)
Other comprehensive (loss) income before reclassifications		(35,797)		20,355		(88)		(15,530)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,929		—		5,929
Net current-period other comprehensive (loss) income		(35,797)		26,284		(88)		(9,601)
Ending balance	$	(171,737)	$	35,547	$	(513)	$	(136,703)

The reclassifications out of accumulated other comprehensive income (loss) consisted of the following during the nine months ended September 30:


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense

Realized gain on sale of marketable securities	$	—	$	21,541	Other income

Derivative Financial Instruments

We had the following Euro:USD forward contracts designated as net investment hedges at September 30, 2018 and December 31, 2017 (in millions):


			Asset (Liability) Value as of
			September 30,		December 31,
Notional Value		Maturity Date	2018		2017
€	50.0	May 15, 2019		0.4		(2.4)
€	50.0	May 15, 2019		(2.1)		(4.9)
€	50.0	May 15, 2020		(2.9)		(5.2)
€	50.0	May 14, 2021		(3.6)		(5.5)

Asset balances in the above table are included in deferred costs and other assets. Liability balances in the above table are included in other liabilities.

New Accounting Pronouncements

- Definition

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.

+ References + Details

Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Significant Accounting Policies

Schedule of carrying amount of noncontrolling interests


	As of		As of
	September 30,		December 31,
	2018		2017
Limited partners’ interests in the Operating Partnership	$	509,943	$	548,858
Nonredeemable noncontrolling interests in properties, net		3,942		3,738
Total noncontrolling interests reflected in equity	$	513,885	$	552,596

Schedule of rollforward of noncontrolling interests


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling interests, beginning of period	$	507,604		564,444	$	552,596	$	649,464
Net income attributable to noncontrolling interests after preferred distributions and income attributable to redeemable noncontrolling interests in consolidated properties		84,452		78,405		261,665		209,743
Distributions to noncontrolling interest holders		(93,637)		(86,125)		(277,550)		(254,026)
Other comprehensive (loss) income allocable to noncontrolling interests:
Unrealized gain (loss) on derivative hedge agreements		717		(1,135)		2,710		(4,116)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings		214		(2,555)		785		(1,887)
Currency translation adjustments		(1,573)		1,712		(4,944)		5,511
Changes in available-for-sale securities and other		(3)		895		(12)		846
		(645)		(1,083)		(1,461)		354
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership		(74,990)		(7,350)		(127,707)		(75,685)
Units issued to limited partners		84,103		—		84,103		—
Units exchanged for common shares		(934)		(252)		(1,004)		(1,605)
Units redeemed		—		—		(572)		—
Long-term incentive performance units		7,885		9,374		23,654		28,932
Contributions by noncontrolling interests, net, and other		47		51		161		287
Noncontrolling interests, end of period	$	513,885	$	557,464	$	513,885	$	557,464

Schedule of changes in components of accumulated other comprehensive income (loss) net of noncontrolling interest


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(118,138)	$	8,055	$	(370)	$	(110,453)
Other comprehensive (loss) income before reclassifications		(30,853)		17,645		(76)		(13,284)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,144		—		5,144
Net current-period other comprehensive (loss) income		(30,853)		22,789		(76)		(8,140)
Ending balance	$	(148,991)	$	30,844	$	(446)	$	(118,593)

Schedule of reclassifications out of accumulated other comprehensive income (loss)


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense
		785		955	Net income attributable to noncontrolling interests
	$	(5,144)	$	(6,283)

Realized gain on sale of marketable securities	$	—	$	21,541	Other income
		—		(2,843)	Net income attributable to noncontrolling interests
	$	—	$	18,698

Schedule of Euro:USD forward contracts

We had the following Euro:USD forward contracts designated as net investment hedges at September 30, 2018 and December 31, 2017 (in millions):


			Asset (Liability) Value as of
			September 30,		December 31,
Notional Value		Maturity Date	2018		2017
€	50.0	May 15, 2019		0.4		(2.4)
€	50.0	May 15, 2019		(2.1)		(4.9)
€	50.0	May 15, 2020		(2.9)		(5.2)
€	50.0	May 14, 2021		(3.6)		(5.5)

Simon Property Group, L.P.

Significant Accounting Policies

Schedule of rollforward of noncontrolling interests


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Noncontrolling nonredeemable interests in properties, net — beginning of period	$	3,632		4,264	$	3,738	$	5,116
Net income attributable to noncontrolling nonredeemable interests		318		316		1,063		1,388
Distributions to noncontrolling nonredeemable interestholders		(56)		(800)		(1,020)		(2,960)
Contributions by noncontrolling nonredeemable interests, net, and other		48		51		161		287
Noncontrolling nonredeemable interests in properties, net — end of period	$	3,942	$	3,831	$	3,942	$	3,831

Schedule of changes in components of accumulated other comprehensive income (loss) net of noncontrolling interest


					Net unrealized
	Currency		Accumulated		losses on
	translation		derivative		marketable
	adjustments		gains, net		securities		Total
Beginning balance	$	(135,940)	$	9,263	$	(425)	$	(127,102)
Other comprehensive (loss) income before reclassifications		(35,797)		20,355		(88)		(15,530)
Amounts reclassified from accumulated other comprehensive income (loss)		—		5,929		—		5,929
Net current-period other comprehensive (loss) income		(35,797)		26,284		(88)		(9,601)
Ending balance	$	(171,737)	$	35,547	$	(513)	$	(136,703)

Schedule of reclassifications out of accumulated other comprehensive income (loss)


	2018		2017
	Amount reclassified		Amount reclassified
Details about accumulated other	from accumulated		from accumulated
comprehensive income (loss)	other comprehensive		other comprehensive		Affected line item where
components:	income (loss)		income (loss)		net income is presented
Accumulated derivative losses, net	$	(5,929)	$	(7,238)	Interest expense

Realized gain on sale of marketable securities	$	—	$	21,541	Other income

Per Share and Per Unit Data (Tables)

9 Months Ended

Sep. 30, 2018

Per Share And Per Unit Data

Schedule of computation of basic and diluted earnings per share and basic and diluted earnings per unit


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2018		2017		2018		2017
Net Income attributable to Common Stockholders — Basic and Diluted	$	556,267	$	513,783	$	1,723,925	$	1,373,509
Weighted Average Shares Outstanding — Basic and Diluted		309,294,045		310,853,299		309,739,557		311,740,360

Simon Property Group, L.P.

Per Share And Per Unit Data

Schedule of computation of basic and diluted earnings per share and basic and diluted earnings per unit


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2018		2017		2018		2017
Net Income attributable to Unitholders — Basic and Diluted	$	640,402	$	591,872	$	1,984,527	$	1,581,864
Weighted Average Units Outstanding — Basic and Diluted		356,073,080		358,115,572		356,562,262		359,029,893

Investment in Unconsolidated Entities (Tables)

9 Months Ended

Sep. 30, 2018

Investment in Unconsolidated Entities

Summary of equity method investments and share of income from such investments, balance sheet


	September 30,		December 31,
	2018		2017
Assets:
Investment properties, at cost	$	18,632,287	$	18,328,747
Less - accumulated depreciation		6,672,267		6,371,363
		11,960,020		11,957,384
Cash and cash equivalents		1,013,153		956,084
Tenant receivables and accrued revenue, net		403,315		403,125
Deferred costs and other assets		395,144		355,585
Total assets	$	13,771,632	$	13,672,178
Liabilities and Partners’ Deficit:
Mortgages	$	15,231,476	$	14,784,310
Accounts payable, accrued expenses, intangibles, and deferred revenue		903,599		1,033,674
Other liabilities		351,116		365,857
Total liabilities		16,486,191		16,183,841
Preferred units		67,450		67,450
Partners’ deficit		(2,782,009)		(2,579,113)
Total liabilities and partners’ deficit	$	13,771,632	$	13,672,178
Our Share of:
Partners’ deficit	$	(1,204,237)	$	(1,144,620)
Add: Excess Investment		1,614,277		1,733,063
Our net Investment in unconsolidated entities, at equity	$	410,040	$	588,443

Summary of equity method investments and share of income from such investments, statements of operations


	For The Three				For The Nine
	Months Ended				Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
REVENUE:
Minimum rent	$	483,685	$	466,601	$	1,443,617	$	1,383,361
Overage rent		52,417		52,560		163,144		150,376
Tenant reimbursements		222,153		215,774		666,068		644,020
Other income		73,259		74,208		232,747		210,287
Total revenue		831,514		809,143		2,505,576		2,388,044
OPERATING EXPENSES:
Property operating		151,873		145,288		437,718		410,301
Depreciation and amortization		161,964		156,682		488,098		469,884
Real estate taxes		60,654		54,668		197,497		185,228
Repairs and maintenance		20,035		18,811		63,968		59,512
Advertising and promotion		20,318		19,837		65,425		63,871
Provision for credit losses		1,300		1,063		13,378		7,629
Other		43,916		45,174		143,533		133,558
Total operating expenses		460,060		441,523		1,409,617		1,329,983
Operating Income		371,454		367,620		1,095,959		1,058,061
Interest expense		(163,855)		(149,746)		(505,540)		(438,393)
Gain on sale or disposal of, or recovery on, assets and interests in unconsolidated entities, net		—		—		25,792		—
Net Income	$	207,599	$	217,874	$	616,211	$	619,668
Third-Party Investors’ Share of Net Income	$	101,750	$	110,581	$	304,174	$	314,531
Our Share of Net Income		105,849		107,293		312,037		305,137
Amortization of Excess Investment		(21,526)		(22,608)		(64,447)		(68,045)
Our Share of Gain on Sale or Disposal of, or Recovery on, Assets and Interests in Unconsolidated Entities, net		—		—		(9,672)		—
Income from Unconsolidated Entities	$	84,323	$	84,685	$	237,918	$	237,092

Debt (Tables)

9 Months Ended

Sep. 30, 2018

Debt

Schedule of fair value of financial instruments and the related discount rate assumptions


	September 30,			December 31,
	2018			2017
Fair value of fixed rate mortgages and unsecured indebtedness	$	22,554		$	24,003
Weighted average discount rates assumed in calculation of fair value for fixed rate mortgages		4.96	%		4.25	%
Weighted average discount rates assumed in calculation of fair value for unsecured indebtedness		4.80	%		4.10	%

Equity (Tables)

9 Months Ended

Sep. 30, 2018

Schedule of preferred units of the Operating Partnership and the amount of the noncontrolling redeemable interests in properties


	As of		As of
	September 30,		December 31,
	2018		2017
7.50% Cumulative Redeemable Preferred Units, 260,000 units authorized, 255,373 issued and outstanding	$	25,537	$	25,537
Other noncontrolling redeemable interests in properties		172,400		164,943
Limited partners’ preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties	$	197,937	$	190,480

Schedule of LTIP units earned and aggregate grant date fair values adjusted for estimated forfeitures


LTIP Program	LTIP Units Earned	Grant Date Fair Value of TSR Award	Grant Date Target Value of FFO-Based Award
2013-2015 LTIP program	466,405	$28.5 million	—
2014-2016 LTIP program	120,314	$27.5 million	—
2015-2017 LTIP program	—	$25.1 million	—
2016-2018 LTIP program	To be determined in 2019	$26.3 million	—
2018 LTIP program - Tranche A	To be determined in 2020	$6.25 million	$6.25 million
2018 LTIP program - Tranche B	To be determined in 2021	$6.25 million	$6.25 million

Reconciliation of carrying amounts of equity


					Accumulated						Common
					Other		Capital in				Stock
	Preferred		Common		Comprehensive		Excess of		Accumulated		Held in		Noncontrolling		Total
	Stock		Stock		Income (Loss)		Par Value		Deficit		Treasury		interests		Equity
January 1, 2018	$	43,077	$	32	$	(110,453)	$	9,614,748	$	(4,782,173)	$	(1,079,063)	$	552,596	$	4,238,764
Exchange of limited partner units for common shares								1,004						(1,004)		—
Issuance of limited partner units														84,103		84,103
Treasury stock purchase												(307,296)				(307,296)
Redemption of limited partner units								(7,047)						(572)		(7,619)
LTIP units														23,654		23,654
Cumulative effect of accounting change										7,264						7,264
Purchase and disposition of noncontrolling interests, net and other		(247)						308		(18,663)		5,740		161		(12,701)
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership								127,707						(127,707)		—
Distributions to common stockholders and limited partners, excluding Operating Partnership preferred interests										(1,829,610)				(276,530)		(2,106,140)
Distributions to other noncontrolling interest partners														(1,020)		(1,020)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties						(8,140)				1,726,428				260,204		1,978,492
September 30, 2018	$	42,830	$	32	$	(118,593)	$	9,736,720	$	(4,896,754)	$	(1,380,619)	$	513,885	$	3,897,501

Simon Property Group, L.P.

Schedule of preferred units of the Operating Partnership and the amount of the noncontrolling redeemable interests in properties


	As of		As of
	September 30,		December 31,
	2018		2017
7.50% Cumulative Redeemable Preferred Units, 260,000 units authorized, 255,373 issued and outstanding	$	25,537	$	25,537
Other noncontrolling redeemable interests in properties		172,400		164,943
Total preferred units, at liquidation value, and noncontrolling redeemable interests in properties	$	197,937	$	190,480

Reconciliation of carrying amounts of equity


	Preferred		Simon (Managing		Limited		Noncontrolling		Total
	Units		General Partner)		Partners		interests		Equity
January 1, 2018	$	43,077	$	3,643,091	$	548,858	$	3,738	$	4,238,764
Issuance of limited partner units						84,103				84,103
Limited partner units exchanged to units				1,004		(1,004)				—
Treasury unit purchase				(307,296)						(307,296)
Redemption of limited partner units				(7,047)		(572)				(7,619)
LTIP Units						23,654				23,654
Cumulative effect of accounting change				7,264						7,264
Purchase and disposition of noncontrolling interests, net and other		(247)		(12,615)				161		(12,701)
Adjustment to limited partners’ interest from change in ownership in the Operating Partnership				127,707		(127,707)				—
Distributions to limited partners, excluding preferred interests classified as temporary equity		(2,503)		(1,827,107)		(276,530)		(1,020)		(2,107,160)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties		2,503		1,715,785		259,141		1,063		1,978,492
September 30, 2018	$	42,830	$	3,340,786	$	509,943	$	3,942	$	3,897,501

Organization (Details)	Sep. 30, 2018 state country property
U.S. and Puerto Rico
Real Estate Properties
Number of properties	207
Number of U.S. states containing property locations \| state	37
U.S. and Puerto Rico \| Malls
Real Estate Properties
Number of properties	107
U.S. and Puerto Rico \| Premium Outlets
Real Estate Properties
Number of properties	69
U.S. and Puerto Rico \| The Mills
Real Estate Properties
Number of properties	14
U.S. and Puerto Rico \| Community/Lifestyle Centers
Real Estate Properties
Number of properties	4
U.S. and Puerto Rico \| Other shopping centers or outlet centers
Real Estate Properties
Number of properties	13
Japan \| Premium Outlets
Real Estate Properties
Number of properties	9
South Korea \| Premium Outlets
Real Estate Properties
Number of properties	4
Canada \| Premium Outlets
Real Estate Properties
Number of properties	3
Canada \| Designer Outlets
Real Estate Properties
Number of properties	1
Malaysia \| Premium Outlets
Real Estate Properties
Number of properties	2
Mexico \| Premium Outlets
Real Estate Properties
Number of properties	1
Europe \| Klepierre
Real Estate Properties
Ownership percentage	21.20%
Number of countries \| country	16
Europe \| Designer Outlets
Real Estate Properties
Number of properties	8
Europe \| Designer Outlets \| Consolidated properties
Real Estate Properties
Number of properties	6
Italy \| Designer Outlets
Real Estate Properties
Number of properties	2
Netherlands \| Designer Outlets
Real Estate Properties
Number of properties	2
Austria \| Designer Outlets
Real Estate Properties
Number of properties	1
Germany \| Designer Outlets
Real Estate Properties
Number of properties	1
France \| Designer Outlets
Real Estate Properties
Number of properties	1
United Kingdom \| Designer Outlets
Real Estate Properties
Number of properties	1

Basis of Presentation (Details) - property	9 Months Ended		12 Months Ended
Basis of Presentation (Details) - property	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Real Estate Properties
Total number of joint venture properties	81
Number of joint venture properties managed by the entity	57
Number of International joint venture properties	20
Number of joint venture properties managed by others	24
Simon Property Group, L.P.
Ownership interest:
Ownership interest in the Operating Partnership (as a percent)	86.80%		86.90%
Simon Property Group, L.P. \| Weighted average
Ownership interest:
Ownership interest in the Operating Partnership (as a percent)	86.90%	86.80%
Wholly owned properties
Real Estate Properties
Number of properties	135
Partially owned properties
Real Estate Properties
Number of properties	19

Summary of Significant Accounting Policies - Equity Instruments and Investments (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
	Jul. 26, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Equity Instruments and Investments
Equity instruments with readily determinable fair value			$ 97,200		$ 88,300
Equity instruments without readily determinable fair values			176,400		186,900
Proceeds from sale of investment	$ 53,900			$ 53,923
Debt securities of our captive insurance companies			$ 66,800		$ 55,700
Other income
Equity Instruments and Investments
Gain on sale of investment		$ 21,500		$ 21,500
Debt Securities \| Securities in captive insurance subsidiary portfolio \| Minimum
Equity Instruments and Investments
Investment maturity period			1 year
Debt Securities \| Securities in captive insurance subsidiary portfolio \| Maximum
Equity Instruments and Investments
Investment maturity period			10 years

Summary of Significant Accounting Policies - Fair Value Measurements (Details) $ in Millions	Sep. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Fair Value Measurements
Number of investments for which fair value is measured on a recurring basis using Level 3 inputs \| item	0
Level 2 \| Recurring
Fair Value Measurements
Interest rate swap agreements and foreign currency forward contracts, gross asset balance	$ 12.9
Interest rate swap agreements and foreign currency forward contracts, gross liability balance	$ 8.6	$ 18.1

Summary of Significant Accounting Policies - Noncontrolling Interests, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Significant Accounting Policies
Limited partners' interests in the Operating Partnership	$ 509,943		$ 548,858
Nonredeemable noncontrolling interests in properties, net	3,942		3,738
Total noncontrolling interests reflected in equity	$ 513,885	$ 507,604	$ 552,596	$ 557,464	$ 564,444	$ 649,464

Summary of Significant Accounting Policies - Rollforward Of Noncontrolling Interest, Simon Group Property, Inc. (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Noncontrolling interests:
Noncontrolling interests, beginning of period	$ 507,604	$ 564,444	$ 552,596	$ 649,464
Net income attributable to noncontrolling interests after preferred distributions and income attributable to redeemable noncontrolling interests in consolidated properties	84,452	78,405	261,665	209,743
Distributions to noncontrolling interest holders	(93,637)	(86,125)	(277,550)	(254,026)
Other comprehensive (loss) income allocable to noncontrolling interests:
Unrealized gain (loss) on derivative hedge agreements	717	(1,135)	2,710	(4,116)
Net loss (gain) reclassified from accumulated other comprehensive loss into earnings	214	(2,555)	785	(1,887)
Currency translation adjustments	(1,573)	1,712	(4,944)	5,511
Changes in available-for-sale securities and other	(3)	895	(12)	846
Other comprehensive income (loss)	(645)	(1,083)	(1,461)	354
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(74,990)	(7,350)	(127,707)	(75,685)
Units issued to limited partners	84,103		84,103
Units exchanged for common shares	(934)	(252)	(1,004)	(1,605)
Units redeemed			(572)
Long-term incentive performance units	7,885	9,374	23,654	28,932
Contributions by noncontrolling nonredeemable interests, net, and other	47	51	161	287
Noncontrolling interests, end of period	$ 513,885	$ 557,464	$ 513,885	$ 557,464

Summary of Significant Accounting Policies - Rollforward Of Noncontrolling Interest, Simon Group Property L.P. (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Noncontrolling interests:
Net income attributable to noncontrolling nonredeemable interests	$ 84,452	$ 78,405	$ 261,665	$ 209,743
Distributions to noncontrolling nonredeemable interest holders	(93,637)	(86,125)	(277,550)	(254,026)
Contributions by noncontrolling nonredeemable interests, net, and other	47	51	161	287
Simon Property Group, L.P.
Noncontrolling interests:
Noncontrolling nonredeemable interests in properties, beginning of period	3,632	4,264	3,738	5,116
Net income attributable to noncontrolling nonredeemable interests	318	316	1,063	1,388
Distributions to noncontrolling nonredeemable interest holders	(56)	(800)	(1,020)	(2,960)
Contributions by noncontrolling nonredeemable interests, net, and other	48	51	161	287
Noncontrolling nonredeemable interests in properties, end of period	$ 3,942	$ 3,831	$ 3,942	$ 3,831

Summary of Significant Accounting Policies - AOCI, Simon Property Group, Inc. (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Changes in accumulated other comprehensive income (loss)
Beginning balance	$ 3,686,168
Ending balance	3,383,616
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Beginning balance	(110,453)
Other comprehensive (loss) income before reclassifications	(13,284)
Amounts reclassified from accumulated other comprehensive income (loss)	5,144
Net current-period other comprehensive (loss) income	(8,140)
Ending balance	(118,593)
Currency translation adjustments
Changes in accumulated other comprehensive income (loss)
Beginning balance	(118,138)
Other comprehensive (loss) income before reclassifications	(30,853)
Net current-period other comprehensive (loss) income	(30,853)
Ending balance	(148,991)
Accumulated derivative gains (losses), net
Changes in accumulated other comprehensive income (loss)
Beginning balance	8,055
Other comprehensive (loss) income before reclassifications	17,645
Amounts reclassified from accumulated other comprehensive income (loss)	5,144
Net current-period other comprehensive (loss) income	22,789
Ending balance	30,844
Net unrealized losses on marketable securities
Changes in accumulated other comprehensive income (loss)
Beginning balance	(370)
Other comprehensive (loss) income before reclassifications	(76)
Net current-period other comprehensive (loss) income	(76)
Ending balance	$ (446)

Summary of Significant Accounting Policies - Reclassification Out of AOCI, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Significant Accounting Policies
Interest expense	$ (199,469)	$ (199,032)	$ (611,585)	$ (604,408)
Net income attributable to noncontrolling interests	(85,111)	(78,018)	(262,722)	(209,070)
Other Income.	90,563	90,161	286,491	219,796
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS	$ 556,267	$ 513,783	1,723,925	1,373,509
Accumulated derivative losses, net, including noncontrolling interests \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense			(5,929)	(7,238)
Accumulated derivative losses, attributable to noncontrolling interests \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests			785	955
Accumulated derivative gains (losses), net \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS			$ (5,144)	(6,283)
Realized gains on sales of marketable securities, including Portion Attributable to Noncontrolling Interest \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Other Income.				21,541
Realized gains on sales of marketable securities, attributable to Noncontrolling Interest \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests				(2,843)
Net unrealized losses on marketable securities \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS				$ 18,698

Summary of Significant Accounting Policies - AOCI, Simon Property Group L.P. (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Simon Property Group, L.P.
Changes in accumulated other comprehensive income (loss)
Beginning Balance	$ 4,235,026
Ending balance	3,893,559
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss)
Other comprehensive (loss) income before reclassifications	(13,284)
Amounts reclassified from accumulated other comprehensive income (loss)	5,144
Net current-period other comprehensive (loss) income	(8,140)
Accumulated Other Comprehensive Income (Loss) \| Simon Property Group, L.P.
Changes in accumulated other comprehensive income (loss)
Beginning Balance	(127,102)
Other comprehensive (loss) income before reclassifications	(15,530)
Amounts reclassified from accumulated other comprehensive income (loss)	5,929
Net current-period other comprehensive (loss) income	(9,601)
Ending balance	(136,703)
Currency translation adjustments
Changes in accumulated other comprehensive income (loss)
Other comprehensive (loss) income before reclassifications	(30,853)
Net current-period other comprehensive (loss) income	(30,853)
Currency translation adjustments \| Simon Property Group, L.P.
Changes in accumulated other comprehensive income (loss)
Beginning Balance	(135,940)
Other comprehensive (loss) income before reclassifications	(35,797)
Net current-period other comprehensive (loss) income	(35,797)
Ending balance	(171,737)
Accumulated derivative gains (losses), net
Changes in accumulated other comprehensive income (loss)
Other comprehensive (loss) income before reclassifications	17,645
Amounts reclassified from accumulated other comprehensive income (loss)	5,144
Net current-period other comprehensive (loss) income	22,789
Accumulated derivative gains (losses), net \| Simon Property Group, L.P.
Changes in accumulated other comprehensive income (loss)
Beginning Balance	9,263
Other comprehensive (loss) income before reclassifications	20,355
Amounts reclassified from accumulated other comprehensive income (loss)	5,929
Net current-period other comprehensive (loss) income	26,284
Ending balance	35,547
Net unrealized losses on marketable securities
Changes in accumulated other comprehensive income (loss)
Other comprehensive (loss) income before reclassifications	(76)
Net current-period other comprehensive (loss) income	(76)
Net unrealized losses on marketable securities \| Simon Property Group, L.P.
Changes in accumulated other comprehensive income (loss)
Beginning Balance	(425)
Other comprehensive (loss) income before reclassifications	(88)
Net current-period other comprehensive (loss) income	(88)
Ending balance	$ (513)

Summary of Significant Accounting Policies - Reclassification Out Of AOCI, Simon Property Group, L.P. (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Significant Accounting Policies
Interest expense	$ (199,469)	$ (199,032)	$ (611,585)	$ (604,408)
Other Income.	90,563	90,161	286,491	219,796
Simon Property Group, L.P.
Significant Accounting Policies
Interest expense	(199,469)	(199,032)	(611,585)	(604,408)
Other Income.	$ 90,563	$ 90,161	286,491	219,796
Accumulated derivative gains (losses), net \| Simon Property Group, L.P. \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense			$ (5,929)	(7,238)
Net unrealized losses on marketable securities \| Simon Property Group, L.P. \| Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Other Income.				$ 21,541

Summary of Significant Accounting Policies - Derivative Financial Instruments (Details) € in Millions, $ in Millions, ¥ in Billions	Jul. 10, 2018 USD ($)	Sep. 30, 2018 USD ($) DerivativeInstrument item	Sep. 30, 2018 EUR (€) DerivativeInstrument item	Jul. 10, 2018 JPY (¥)	Jul. 10, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($) DerivativeInstrument	Dec. 31, 2017 EUR (€) DerivativeInstrument
Derivative Financial Instruments
Number of credit-risk-related hedging or derivative activities \| item		0	0
Interest rate swap \| Designated as Hedging Instrument
Derivative Financial Instruments
Number of Instruments \| DerivativeInstrument		0	0					0	0
USD-Euro currency forward contract \| May 15, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €			€ 50.0						€ 50.0
Forward contract net, fair value		$ 0.4						$ (2.4)
USD-Euro currency forward contract \| May 15, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €			50.0						50.0
Forward contract net, fair value		(2.1)						(4.9)
USD-Euro currency forward contract \| May 15, 2020 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €			50.0						50.0
Forward contract net, fair value		(2.9)						(5.2)
USD-Euro currency forward contract \| May 14, 2021 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €			€ 50.0						€ 50.0
Forward contract net, fair value		(3.6)						(5.5)
US denominated cross currency swap \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount					$ 200.1	$ 150.0
Swapping interest rate				4.38%	4.38%	4.38%	4.38%
Yen denominated cross currency swap \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| ¥				¥ 22.3
Fixed exchange rate				1.19%	1.19%
Yen denominated cross currency swap \| Deferred costs and other assets \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Fair value of cross currency		4.0
Euro denominated cross currency swap \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €							€ 121.6
Fixed exchange rate						1.37%	1.37%
Euro denominated cross currency swap \| Deferred costs and other assets \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Interest rate derivative asset, fair value		8.0
Simon Property Group, L.P.
Derivative Financial Instruments
Gross accumulated other comprehensive income related to derivative activities		35.6						$ 9.3
Simon Property Group, L.P. \| Credit Facility \| Unsecured Debt
Derivative Financial Instruments
Maximum borrowing capacity		$ 4,000.0
Simon Property Group, L.P. \| Yen \| Credit Facility \| Unsecured Debt
Derivative Financial Instruments
Debt repaid	$ 201.3

Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Jan. 01, 2018
New Accounting Pronouncements
Cumulative effect adjustment			$ 7,264
Retained Earnings (Accumulated Deficit)	$ (4,782,173)		(4,896,754)
Accounting Standards Update 2014-09 \| Maximum
New Accounting Pronouncements
Percentage of revenues impacted by ASU (as a percent)	6.00%	7.00%
Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements
Retained Earnings (Accumulated Deficit)				$ 0
Accounting Standards Update 2016-01 \| Adjustment
New Accounting Pronouncements
Cumulative effect adjustment				7,300
Accounting Standards Update 2016-02 \| Scenario Forecast Adjustment
New Accounting Pronouncements
Future minimum gross lease payments			$ 782,800
Accounting Standards Update 2017-05 \| Adjustment
New Accounting Pronouncements
Cumulative effect adjustment				$ 0

Per Share and Per Unit Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Per Share And Per Unit Data
Net Income attributable to Common Stockholders - Basic	$ 556,267	$ 513,783	$ 1,723,925	$ 1,373,509
Net Income attributable to Common Stockholders - Diluted	$ 556,267	$ 513,783	$ 1,723,925	$ 1,373,509
Weighted Average Shares Outstanding — Basic and Diluted	309,294,045	310,853,299	309,739,557	311,740,360
Simon Property Group, L.P.
Per Share And Per Unit Data
Net Income attributable to Common Stockholders - Basic	$ 640,402	$ 591,872	$ 1,984,527	$ 1,581,864
Net Income attributable to Common Stockholders - Diluted	$ 640,402	$ 591,872	$ 1,984,527	$ 1,581,864
Weighted Average Shares Outstanding — Basic and Diluted	356,073,080	358,115,572	356,562,262	359,029,893

Investments in Unconsolidated Entities - Real Estate Joint Ventures and Investments (Details) $ in Millions	Sep. 30, 2018 USD ($) property	Dec. 31, 2017 USD ($)
Investment in Unconsolidated Entities
Total number of joint venture properties \| property	81
Construction and other related party loans
Investment in Unconsolidated Entities
Loans to related party \| $	$ 86.0	$ 87.0

Investments in Unconsolidated Entities - Unconsolidated Entity Transactions (Details)					1 Months Ended		3 Months Ended				9 Months Ended
	Sep. 25, 2018 USD ($) shares	Jun. 07, 2018 USD ($)	Sep. 15, 2016 item	Sep. 30, 2015 property	Sep. 30, 2018 USD ($) property	Apr. 30, 2018 USD ($)	Sep. 30, 2018 USD ($) property	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2018 USD ($) property	Sep. 30, 2017 USD ($)	Dec. 31, 2018	Sep. 11, 2018 ft²	Dec. 31, 2017	May 31, 2017
Investment in Unconsolidated Entities
Insurance proceeds recorded as business interruption											$ 16,160,000
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net											144,949,000	$ 4,989,000
Gain on interest in unconsolidated entities											35,621,000
Share of net income, net of amortization of our excess investment							$ 134,408,000	$ 116,110,000			$ 325,263,000	277,212,000
Outlets at Orange
Investment in Unconsolidated Entities
Percentage of equity stake acquired	50.00%
Ownership interest after acquisition (as a percent)					100.00%		100.00%				100.00%
Simon Property Group, L.P.
Investment in Unconsolidated Entities
Insurance proceeds recorded as business interruption											$ 16,160,000
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net											144,949,000	4,989,000
Gain on interest in unconsolidated entities											35,621,000
Share of net income, net of amortization of our excess investment							$ 134,408,000	116,110,000			325,263,000	277,212,000
Simon Property Group, L.P. \| Outlets at Orange
Investment in Unconsolidated Entities
Number of units issued in connection with acquisition of the remaining interest in orange outlet \| shares	475,183
Business acquisition price	$ 176.99
Colorado Mills
Investment in Unconsolidated Entities
Impairment charges									$ 32,500,000
Insurance proceeds recorded as business interruption											58,300,000
Gain on business interruption											$ 25,800,000
Aventura Mall
Investment in Unconsolidated Entities
Loan defeasance charge		$ 30,900,000
Write off of deferred debt issuance cost		6,500,000
Mortgages \| Aventura Mall
Investment in Unconsolidated Entities
Debt refinanced		1,200,000,000
Construction loan \| Aventura Mall
Investment in Unconsolidated Entities
Debt refinanced		200,800,000
4.12% fixed interest rate mortgage maturing July 2028 \| Aventura Mall
Investment in Unconsolidated Entities
Debt issued		$ 1,750,000,000
Fixed interest rate (as a percent)		4.12%
Macerich
Investment in Unconsolidated Entities
Ownership interest (as a percent)					50.00%		50.00%				50.00%
Area of property (in square feet) \| ft²														400,000
Additional area of a real estate property \| ft²														166,000
Contribution to form joint venture					$ 13,100,000
Aventura Mall
Investment in Unconsolidated Entities
Ownership interest (as a percent)		33.30%
Share of early debt repayment charge		$ 12,500,000
Colorado Mills
Investment in Unconsolidated Entities
Ownership interest (as a percent)																37.50%
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net											$ 9,700,000
Aeropostale
Investment in Unconsolidated Entities
Number of joint ventures \| item			2
Aeropostale Retail Operations
Investment in Unconsolidated Entities
Ownership interest (as a percent)					44.95%		44.95%				44.95%
Authentic Brands Group LLC
Investment in Unconsolidated Entities
Ownership interest (as a percent)					5.78%		5.78%				5.78%
Gain on interest in unconsolidated entities						$ 35,600,000
HBS
Investment in Unconsolidated Entities
Ownership interest (as a percent)					11.70%		11.70%				11.70%				11.70%
Number of properties contributed to form joint venture \| property					42		42				42
Number of Kaufhof properties purchased by the joint venture \| property				41
Contributions for improvements to properties					$ 68,300,000		$ 68,300,000				$ 68,300,000
Contribution to form joint venture										$ 178,500,000
Share of net income, net of amortization of our excess investment							$ 4,300,000	$ 4,800,000			11,900,000	11,300,000
Total revenues											258,800,000	265,800,000
Total operating income											162,200,000	246,900,000
Consolidated net income											$ 90,600,000	$ 176,200,000
HBS \| Forecast
Investment in Unconsolidated Entities
Ownership interest (as a percent)													11.70%

Investments in Unconsolidated Entities - European Investments (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) property $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) property $ / shares shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) property
Investment in Unconsolidated Entities
Income from unconsolidated entities	$ 134,408	$ 116,110	$ 325,263	$ 277,212
Klepierre \| Disposed by Sales \| Shopping centers
Investment in Unconsolidated Entities
Gain (loss) on disposition of interest in properties			$ 13,400	5,000
European Joint Venture \| Designer Outlet properties
Investment in Unconsolidated Entities
Number of properties \| property	9		9		9
European Property Management and Development \| Designer Outlet properties
Investment in Unconsolidated Entities
Ownership interest (as a percent)	50.00%		50.00%
European Property Management and Development \| Designer Outlet properties \| Minimum
Investment in Unconsolidated Entities
Ownership interest (as a percent)	45.00%		45.00%
European Property Management and Development \| Designer Outlet properties \| Maximum
Investment in Unconsolidated Entities
Ownership interest (as a percent)	94.00%		94.00%
Europe \| Klepierre
Investment in Unconsolidated Entities
Shares owned \| shares	63,924,148		63,924,148
Ownership interest (as a percent)	21.20%		21.20%
Quoted market price per share (in dollars per share) \| $ / shares	$ 35.43		$ 35.43
Income from unconsolidated entities	$ 22,400	$ 14,100	$ 70,000	37,200
Total revenues			1,200,000	1,100,000
Total operating income			496,400	406,300
Consolidated net income			$ 485,800	$ 298,300
Europe \| Value Retail PLC
Investment in Unconsolidated Entities
Number of luxury outlets owned and operated \| property	9		9
Number of outlets in which the entity has a minority direct ownership \| property	3		3
Europe \| Value Retail PLC \| Deferred costs and other assets
Investment in Unconsolidated Entities
Vale of equity instruments	$ 140,800		$ 140,800		$ 140,800

Investments in Unconsolidated Entities - Asian Joint Ventures (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment in Unconsolidated Entities
Equity investment	$ 2,281,688	$ 2,266,483
Japan \| Mitsubishi Estate Co., Ltd. \| Premium Outlets
Investment in Unconsolidated Entities
Ownership percentage	40.00%
Equity investment	$ 221,200	230,300
South Korea \| Shinsegae International Co \| Premium Outlets
Investment in Unconsolidated Entities
Ownership percentage	50.00%
Equity investment	$ 159,800	$ 149,100

Investments in Unconsolidated Entities - Combined Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Our Share of:
Investment in unconsolidated entities, at equity	$ 2,281,688	$ 2,266,483
Unconsolidated properties \| Maximum
Our Share of:
Estimated life of investment property	40 years
Equity Method Investees excluding Klepierre, Aeropostale and HBS \| Unconsolidated properties
Assets:
Investment properties, at cost	$ 18,632,287	18,328,747
Less - accumulated depreciation	6,672,267	6,371,363
Investment properties at cost, net	11,960,020	11,957,384
Cash and cash equivalents	1,013,153	956,084
Tenant receivables and accrued revenue, net	403,315	403,125
Deferred costs and other assets	395,144	355,585
Total assets	13,771,632	13,672,178
Liabilities and Partners' Deficit:
Mortgages	15,231,476	14,784,310
Accounts payable, accrued expenses, intangibles, and deferred revenues	903,599	1,033,674
Other liabilities	351,116	365,857
Total liabilities	16,486,191	16,183,841
Preferred units	67,450	67,450
Partners' deficit	(2,782,009)	(2,579,113)
Total liabilities and partners' deficit	13,771,632	13,672,178
Our Share of:
Partners' deficit	(1,204,237)	(1,144,620)
Add: Excess Investment	1,614,277	1,733,063
Investment in unconsolidated entities, at equity	$ 410,040	$ 588,443

Investments in Unconsolidated Entities - Combined Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
OPERATING EXPENSES:
Income from Unconsolidated Entities	$ 134,408	$ 116,110	$ 325,263	$ 277,212
Equity Method Investees excluding Klepierre, Aeropostale and HBS \| Unconsolidated properties
REVENUE:
Minimum rent	483,685	466,601	1,443,617	1,383,361
Overage rent	52,417	52,560	163,144	150,376
Tenant reimbursements	222,153	215,774	666,068	644,020
Other income	73,259	74,208	232,747	210,287
Total revenue	831,514	809,143	2,505,576	2,388,044
OPERATING EXPENSES:
Property operating	151,873	145,288	437,718	410,301
Depreciation and amortization	161,964	156,682	488,098	469,884
Real estate taxes	60,654	54,668	197,497	185,228
Repairs and maintenance	20,035	18,811	63,968	59,512
Advertising and promotion	20,318	19,837	65,425	63,871
Provision for credit losses	1,300	1,063	13,378	7,629
Other	43,916	45,174	143,533	133,558
Total operating expenses	460,060	441,523	1,409,617	1,329,983
Operating Income	371,454	367,620	1,095,959	1,058,061
Interest expense	(163,855)	(149,746)	(505,540)	(438,393)
Gain on sale or disposal of, or recovery on, assets and interests in unconsolidated entities, net			25,792
Net Income	207,599	217,874	616,211	619,668
Third-Party Investors’ Share of Net Income	101,750	110,581	304,174	314,531
Our Share of Net Income	105,849	107,293	312,037	305,137
Amortization of Excess Investment	(21,526)	(22,608)	(64,447)	(68,045)
Our Share of Gain on Sale or Disposal of, or Recovery on, Assets and Interests in Unconsolidated Entities, net			(9,672)
Income from Unconsolidated Entities	$ 84,323	$ 84,685	$ 237,918	$ 237,092

Debt (Details) $ in Thousands, € in Millions					9 Months Ended
Debt (Details) $ in Thousands, € in Millions	Jul. 30, 2018 EUR (€)	Jul. 10, 2018 USD ($)	Feb. 15, 2018 USD ($)	Feb. 14, 2018	Sep. 30, 2018 USD ($) item property	Sep. 25, 2018 USD ($)	Jan. 03, 2018 USD ($)	Dec. 31, 2017 USD ($) item
Debt
Total Mortgages and Unsecured Indebtedness					$ 23,678,264			$ 24,632,463
Outlets at Orange
Debt
Ownership interests acquired (as a percent)						50.00%
Noventa Di Piave Designer Outlet
Debt
Ownership interest (as a percent)	90.00%
Simon Property Group, L.P.
Debt
Total Mortgages and Unsecured Indebtedness					$ 23,678,264			$ 24,632,463
Mortgage Maturing April 1,2024 \| Outlets at Orange
Debt
Fixed mortgage loan						$ 215,000
Fixed rate of interest						4.22%
Fixed Rate 2.00 Mortgage Maturing 2025 \| Noventa Di Piave Designer Outlet
Debt
Fixed mortgage loan \| €	€ 260.0
Fixed rate of interest	2.00%
Variable Rate 1.68 Mortgage Maturing 2020 \| Noventa Di Piave Designer Outlet
Debt
Debt repaid \| €	€ 110.0
Variable rate of interest	1.68%
Unsecured Debt \| Weighted average \| Discount Rate
Fair Value of Debt
Debt percentage- measurement input \| item					4.80			4.10
Unsecured Debt \| Senior unsecured notes \| Simon Property Group, L.P.
Debt
Total Mortgages and Unsecured Indebtedness					$ 15,700,000
Unsecured Debt \| Senior Unsecured Note 1.50% \| Simon Property Group, L.P.
Debt
Amount of debt redeemed							$ 750,000
Interest rate on debt (as a percent)							1.50%
Unsecured Debt \| Credit Facility and the Supplemental Facility
Debt
Available borrowing capacity					6,400,000
Maximum amount outstanding during period					423,100
Credit facility, weighted average amount outstanding					276,200
Letters of credit outstanding					11,600
Unsecured Debt \| Credit Facility \| Simon Property Group, L.P.
Debt
Credit facility, amount outstanding					125,000
Maximum borrowing capacity					4,000,000
Optional expanded maximum borrowing capacity					$ 5,000,000
Additional facility fee (as a percent)					0.10%
Unsecured Debt \| Credit Facility \| Simon Property Group, L.P. \| Yen
Debt
Debt repaid		$ 201,300
Unsecured Debt \| Credit Facility \| Maximum \| Simon Property Group, L.P.
Debt
Percentage of borrowings in currencies other than the U.S. dollar					95.00%
Unsecured Debt \| Credit Facility \| LIBOR \| Simon Property Group, L.P.
Debt
Interest added to reference rate (as a percent)					0.775%
Unsecured Debt \| Supplemental Facility \| Simon Property Group, L.P.
Debt
Maximum borrowing capacity					$ 3,500,000
Optional expanded maximum borrowing capacity			$ 4,500,000
Additional facility fee (as a percent)			0.10%
Unsecured Debt \| Supplemental Facility \| LIBOR \| Simon Property Group, L.P.
Debt
Interest added to reference rate (as a percent)			0.775%	0.80%
Unsecured Debt \| Commercial Paper \| Simon Property Group, L.P.
Debt
Credit facility, amount outstanding					996,900
Maximum borrowing capacity					$ 1,000,000
Weighted average interest rate (as a percent)					2.16%
Secured Debt \| Mortgages
Debt
Total Mortgages and Unsecured Indebtedness					$ 7,000,000			$ 6,900,000
Debt covenants
Number of non-recourse mortgage notes under which the Company and subsidiaries are borrowers \| item					46
Number of properties pledged as collateral \| property					49
Number of cross-defaulted and cross-collateralized mortgage pools \| item					2
Total number of properties pledged as collateral for cross defaulted and cross collateralized mortgages \| property					5
Secured Debt \| 7.79% rate Mortgage
Debt
Debt repaid					$ 86,600
Interest rate on debt (as a percent)					7.79%
Fixed rate mortgages \| Weighted average \| Discount Rate
Fair Value of Debt
Debt percentage- measurement input \| item					4.96			4.25
Book value \| Fixed rate mortgages and unsecured indebtedness
Fair Value of Debt
Fair value of fixed-rate mortgages and unsecured indebtedness					$ 22,800,000			$ 23,400,000
Fair value \| Fixed rate mortgages and unsecured indebtedness
Fair Value of Debt
Fair value of fixed-rate mortgages and unsecured indebtedness					$ 22,554,000			$ 24,003,000

Equity - Shares or Units Activity (Details) $ / shares in Units, $ in Millions			3 Months Ended			9 Months Ended
	Sep. 25, 2018 shares	Feb. 13, 2017 USD ($)	Dec. 31, 2018 $ / shares	Sep. 30, 2018 $ / shares	Sep. 30, 2017 $ / shares	Sep. 30, 2018 USD ($) item $ / shares shares	Sep. 30, 2017 $ / shares shares
Equity
Stock repurchase program, extension period		2 years
Common stock authorized for repurchase \| $		$ 2,000.0
Shares repurchased (in shares) \| shares						1,988,247	2,399,051
Average share price repurchased (in dollars per share) \| $ / shares						$ 154.56	$ 165.14
Common stock dividends paid (in dollars per share) \| $ / shares				$ 2.00	$ 1.80	$ 5.90	5.30
Dividends declared per common share (in dollars per share) \| $ / shares			$ 2.00
Outlets at Orange
Equity
Ownership interests acquired (as a percent)	50.00%
Limited Partners
Equity
Exchange of limited partner units, (in shares) \| shares						92,732
Number of limited partners who received common stock \| item						2
Simon Property Group, L.P.
Equity
Distributions paid per unit (in dollars per share) \| $ / shares				$ 2.00	$ 1.80	$ 5.90	$ 5.30
Simon Property Group, L.P. \| Outlets at Orange
Equity
Number of units issued in connection with acquisition of the remaining interest in orange outlet \| shares	475,183
Simon Property Group, L.P. \| Limited Partners
Equity
Redemption of units \| shares						49,219
Number of limited partners who received common stock \| item						4
Value of units redeemed \| $						$ 7.6

Equity - Temporary Equity (Details) $ in Thousands	9 Months Ended	12 Months Ended
Equity - Temporary Equity (Details) $ in Thousands	Sep. 30, 2018 USD ($) item shares	Dec. 31, 2017 USD ($) item shares
Redeemable preferred stock
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	$ 197,937	$ 190,480
Simon Property Group, L.P.
Redeemable preferred stock
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	$ 197,937	$ 190,480
7.5% Cumulative Redeemable Preferred Units
Redeemable preferred stock
Noncontrolling interests redeemable at amounts in excess of fair value \| item	0	0
Preferred stock stated dividend rate percentage	7.50%	7.50%
Temporary equity, shares authorized \| shares	260,000	260,000
Temporary equity, shares issued \| shares	255,373	255,373
Temporary equity, shares outstanding \| shares	255,373	255,373
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	$ 25,537	$ 25,537
7.5% Cumulative Redeemable Preferred Units \| Simon Property Group, L.P.
Redeemable preferred stock
Preferred stock stated dividend rate percentage	7.50%	7.50%
Temporary equity, shares authorized \| shares	260,000	260,000
Temporary equity, shares issued \| shares	255,373	255,373
Temporary equity, shares outstanding \| shares	255,373	255,373
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	$ 25,537	$ 25,537
Other noncontrolling redeemable interest
Redeemable preferred stock
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	172,400	164,943
Other noncontrolling redeemable interest \| Simon Property Group, L.P.
Redeemable preferred stock
Limited partners' preferred interest in the Operating Partnership and noncontrolling redeemable interests in properties \| $	$ 172,400	$ 164,943

Equity - Stock Based Compensation (Details) $ / shares in Units, $ in Thousands		9 Months Ended		12 Months Ended
	Jul. 06, 2011 USD ($) shares	Sep. 30, 2018 USD ($) item $ / shares shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Dec. 31, 2013 shares
Restricted stock
Stock-based incentive plan awards
Compensation expense, net of capitalization		$ 6,000	$ 7,600
Restricted stock \| Employees
Stock-based incentive plan awards
Vesting period		3 years
Awards earned (in units) \| shares		43,043
Weighted average fair value of shares granted during the period (in dollars per share) \| $ / shares		$ 154.35
Restricted stock \| Non-employee Directors
Stock-based incentive plan awards
Vesting period		1 year
Awards earned (in units) \| shares		12,648
Weighted average fair value of shares granted during the period (in dollars per share) \| $ / shares		$ 158.71
LTIP Retention Award to Chairman and CEO
Stock-based incentive plan awards
Awards earned (in units) \| shares	1,000,000
Grant Date Fair Value	$ 120,300
Service period	8 years
LTIP Retention Award to Chairman and CEO \| A Units
Stock-based incentive plan awards
Awards earned (in units) \| shares						360,000
LTIP Retention Award to Chairman and CEO \| A Units \| Maximum
Stock-based incentive plan awards
Shares reserved for issuance (in shares) \| shares							360,000
LTIP Retention Award to Chairman and CEO \| B Units
Stock-based incentive plan awards
Awards earned (in units) \| shares					360,000
LTIP Retention Award to Chairman and CEO \| B Units \| Maximum
Stock-based incentive plan awards
Shares reserved for issuance (in shares) \| shares							360,000
LTIP Retention Award to Chairman and CEO \| C Units
Stock-based incentive plan awards
Awards earned (in units) \| shares				280,000
LTIP Retention Award to Chairman and CEO \| C Units \| Maximum
Stock-based incentive plan awards
Shares reserved for issuance (in shares) \| shares							280,000
LTIP programs
Stock-based incentive plan awards
Percent of distributions of Operating Partnership that participants are entitled to receive during performance period		10.00%
Vesting period		2 years
Vesting rights percentage		50.00%
Compensation expense, net of capitalization		$ 13,000	$ 9,700
2013-2015 LTIP program \| LTIP Units
Stock-based incentive plan awards
LTIP Units Earned (in units) \| shares		466,405
Grant Date Fair Value		$ 28,500
2014-2016 LTIP program \| LTIP Units
Stock-based incentive plan awards
LTIP Units Earned (in units) \| shares		120,314
Grant Date Fair Value		$ 27,500
2015-2017 LTIP program \| LTIP Units
Stock-based incentive plan awards
Grant Date Fair Value		25,100
2016-2018 LTIP program \| LTIP Units
Stock-based incentive plan awards
Grant Date Fair Value		$ 26,300
2018 LTIP program \| LTIP Units
Stock-based incentive plan awards
Number of tranches \| item		2
Grant Date Fair Value		$ 12,500
2018 LTIP program \| LTIP Units \| Maximum
Stock-based incentive plan awards
Grant Date Target Value		$ 18,750
2018 LTIP program \| LTIP Units \| Tranche A
Stock-based incentive plan awards
Vesting rights percentage		50.00%
Performance period		2 years
Grant Date Fair Value		$ 6,250
Grant Date Target Value		$ 6,250
2018 LTIP program \| LTIP Units \| Tranche B
Stock-based incentive plan awards
Performance period		3 years
Grant Date Fair Value		$ 6,250
Grant Date Target Value		$ 6,250

Equity - Changes in Equity, Simon Property Group, Inc. (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Increase (Decrease) in Stockholders' Equity
Balance	$ 4,238,764
Issuance of limited partner units	84,103
Treasury stock purchase	(307,296)
Redemption of limited partner units	(7,619)
LTIP Units	23,654
Cumulative effect of accounting change	7,264
Purchase and disposition of noncontrolling interests, net and other	(12,701)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(2,106,140)
Distributions to noncontrolling other interest holders	(1,020)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,978,492
Balance	3,897,501
Comprehensive income attributable to preferred interests	1,436
Comprehensive loss attributable to noncontrolling redeemable interests in properties	379
Preferred Stock
Increase (Decrease) in Stockholders' Equity
Balance	43,077
Purchase and disposition of noncontrolling interests, net and other	(247)
Balance	42,830
Common Stock
Increase (Decrease) in Stockholders' Equity
Balance	32
Balance	32
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity
Balance	(110,453)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	(8,140)
Balance	(118,593)
Capital in Excess of Par Value
Increase (Decrease) in Stockholders' Equity
Balance	9,614,748
Exchange of limited partner units for common shares	1,004
Redemption of limited partner units	(7,047)
Purchase and disposition of noncontrolling interests, net and other	308
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	127,707
Balance	9,736,720
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Balance	(4,782,173)
Cumulative effect of accounting change	7,264
Purchase and disposition of noncontrolling interests, net and other	(18,663)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(1,829,610)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,726,428
Balance	(4,896,754)
Common Stock Held in Treasury
Increase (Decrease) in Stockholders' Equity
Balance	(1,079,063)
Treasury stock purchase	(307,296)
Purchase and disposition of noncontrolling interests, net and other	5,740
Balance	(1,380,619)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Balance	552,596
Exchange of limited partner units for common shares	(1,004)
Issuance of limited partner units	84,103
Redemption of limited partner units	(572)
LTIP Units	23,654
Purchase and disposition of noncontrolling interests, net and other	161
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(127,707)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(276,530)
Distributions to noncontrolling other interest holders	(1,020)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	260,204
Balance	$ 513,885

Equity - Changes in Equity, Simon Property Group, L.P. (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Increase (Decrease) in Stockholders' Equity
Issuance of limited partner units	$ 84,103
Redemption of limited partner units	(7,619)
Cumulative effect of accounting change	7,264
Purchase and disposition of noncontrolling interests, net and other	(12,701)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,978,492
Comprehensive income attributable to preferred interests	1,436
Comprehensive loss attributable to noncontrolling redeemable interests in properties	379
Simon Property Group, L.P.
Increase (Decrease) in Stockholders' Equity
Balance	4,238,764
Issuance of limited partner units	84,103
Treasury unit purchase	(307,296)
Redemption of limited partner units	(7,619)
LTIP Units	23,654
Cumulative effect of accounting change	7,264
Purchase and disposition of noncontrolling interests, net and other	(12,701)
Distributions to limited partners, excluding preferred interests classified as temporary equity	(2,107,160)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,978,492
Balance	3,897,501
Comprehensive income attributable to preferred interests	1,436
Comprehensive loss attributable to noncontrolling redeemable interests in properties	379
Simon Property Group, L.P. \| Preferred Stock
Increase (Decrease) in Stockholders' Equity
Balance	43,077
Purchase and disposition of noncontrolling interests, net and other	(247)
Distributions to limited partners, excluding preferred interests classified as temporary equity	(2,503)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	2,503
Balance	42,830
Simon Property Group, L.P. \| Simon (Managing General Partner)
Increase (Decrease) in Stockholders' Equity
Balance	3,643,091
Limited partner units exchanged to units	1,004
Treasury unit purchase	(307,296)
Redemption of limited partner units	(7,047)
Cumulative effect of accounting change	7,264
Purchase and disposition of noncontrolling interests, net and other	(12,615)
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	127,707
Distributions to limited partners, excluding preferred interests classified as temporary equity	(1,827,107)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,715,785
Balance	3,340,786
Simon Property Group, L.P. \| Limited Partners
Increase (Decrease) in Stockholders' Equity
Balance	548,858
Issuance of limited partner units	84,103
Limited partner units exchanged to units	(1,004)
Redemption of limited partner units	(572)
LTIP Units	23,654
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(127,707)
Distributions to limited partners, excluding preferred interests classified as temporary equity	(276,530)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	259,141
Balance	509,943
Simon Property Group, L.P. \| Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Balance	3,738
Purchase and disposition of noncontrolling interests, net and other	161
Distributions to limited partners, excluding preferred interests classified as temporary equity	(1,020)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $379 loss attributable to noncontrolling redeemable interests in properties	1,063
Balance	$ 3,942

Commitments and Contingencies - Guarantees of Indebtedness (Details) - Joint Venture Mortgage and Indebtedness - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Guarantees of Joint Venture Indebtedness:
Loan guarantee	$ 215.5	$ 211.6
Loan guarantees recoverable	$ 10.8	$ 10.8

Commitments and Contingencies - Concentration of Credit Risk (Details)	9 Months Ended
	Sep. 30, 2018
Consolidated revenues \| Concentration of credit risk \| Maximum
Concentration of Credit Risk
Percentage of consolidated revenues from a single customer or tenant	5.00%

Commitments and Contingencies - Hurricane Impacts (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 property	Sep. 30, 2018 USD ($)
Hurricane Impact
Insurance proceeds recorded as business interruption			$ 16,160
PUERTO RICO \| Wholly owned properties \| Loss from Catastrophes
Hurricane Impact
Number of properties significantly damaged \| property		2
Impairment of real estate	$ 19,000
Total insurance proceeds received			50,300
Insurance proceeds received and used for property restoration and remediation			33,300
Insurance proceeds recorded as business interruption			$ 17,000

Real Estate Acquisitions and Dispositions (Details) - USD ($) $ in Millions		9 Months Ended
	Sep. 25, 2018	Sep. 30, 2018
Outlets at Orange
Acquisitions
Ownership interests acquired (as a percent)	50.00%
Outlets at Orange \| Mortgage Maturing April 1,2024
Acquisitions
Fixed mortgage loan	$ 215.0
Fixed rate of interest	4.22%
Outlets at Orange \| Simon Property Group, L.P.
Acquisitions
Number of units issued in connection with acquisition of the remaining interest in orange outlet	475,183
Consideration for the acquisition	$ 84.1
Consolidated properties \| Disposed of by Sales And Means Other than Sale
Dispositions
Nets gains on disposition		$ 144.9
Non-recourse mortgage		$ 200.0