CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Common Stock	Additional Paid-In Capital	Cumulative Dividends In Excess Of Earnings	Accumulated Other Comprehensive Income (Loss)	Total Stockholders’ Equity	Total Noncontrolling Interests
Balance at Dec. 31, 2016		$ 5,941,308	$ 468,081	$ 8,198,890	$ (3,089,734)	$ (29,642)	$ 5,547,595	$ 393,713
Balance (in shares) at Dec. 31, 2016			468,081
Increase (Decrease) in Stockholders' Equity
Net income (loss)		480,558			472,871		472,871	7,687
Other comprehensive income (loss)		5,151				5,151	5,151
Issuance of common stock, net		17,350	$ 998	16,352			17,350
Issuance of common stock, net (in shares)			998
Conversion of DownREIT units to common stock		0	$ 68	2,003			2,071	(2,071)
Conversion of DownREIT units to common stock (in shares)			68
Repurchase of common stock		(4,459)	$ (144)	(4,315)			(4,459)
Repurchase of common stock (in shares)			(144)
Exercise of stock options (in shares)			32
Exercise of stock options		768	$ 32	736			768
Amortization of deferred compensation		10,865		10,865			10,865
Common dividends		(520,779)			(520,779)		(520,779)
Distributions to noncontrolling interests		(19,520)		0				(19,520)
Issuances of noncontrolling interests		1,050						1,050
Deconsolidation of noncontrolling interests		(58,061)		0	0			(58,061)
Balance at Sep. 30, 2017		5,854,231	$ 469,035	8,224,531	(3,137,642)	(24,491)	5,531,433	322,798
Balance (in shares) at Sep. 30, 2017			469,035
Increase (Decrease) in Stockholders' Equity
Cumulative effect of new accounting principle	[1]	79,144			79,144		79,144
Adjusted balance, January 1, 2018		5,674,082	$ 469,436	8,226,113	(3,291,376)	(24,024)	5,380,149	293,933
Balance at Dec. 31, 2017		5,594,938	$ 469,436	8,226,113	(3,370,520)	(24,024)	5,301,005	293,933
Balance (in shares) at Dec. 31, 2017			469,436
Increase (Decrease) in Stockholders' Equity
Net income (loss)		239,091			229,545		229,545	9,546
Other comprehensive income (loss)		19,727				19,727	19,727
Issuance of common stock, net		4,310	$ 601	3,709			4,310
Issuance of common stock, net (in shares)			601
Repurchase of common stock		(3,342)	$ (138)	(3,204)			(3,342)
Repurchase of common stock (in shares)			(138)
Exercise of stock options (in shares)			17
Exercise of stock options		376	$ 17	359			376
Amortization of deferred compensation		13,098		13,098			13,098
Common dividends		(522,566)			(522,566)		(522,566)
Distributions to noncontrolling interests		(13,924)						(13,924)
Issuances of noncontrolling interests		298,929						298,929
Purchase of noncontrolling interests		(69,406)		(50,129)			(50,129)	(19,277)
Balance at Sep. 30, 2018		$ 5,640,375	$ 469,916	$ 8,189,946	$ (3,584,397)	$ (4,297)	$ 5,071,168	$ 569,207
Balance (in shares) at Sep. 30, 2018			469,916

[1] On January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) No. 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (“ASU 2017-05”), and recognized the cumulative-effect of adoption to beginning retained earnings. Refer to Note 2 for a detailed impact of adoption.