CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, unless otherwise specified	Total	Total Stockholders' Equity	Preferred Stock	Common Stock	Additional Paid-In Capital	Cumulative Dividends In Excess Of Earnings	Accumulated Other Comprehensive Income (Loss)	Total Noncontrolling Interests
Balance at Dec. 31, 2011	$ 9,220,622	$ 9,033,482	$ 285,173	$ 408,629	$ 9,383,536	$ (1,024,274)	$ (19,582)	$ 187,140
Balance (in shares) at Dec. 31, 2011			11,820	408,629
Increase (Decrease) in Stockholders' Equity
Net income	600,582	591,512				591,512		9,070
Other comprehensive income (loss)	2,936	2,936					2,936
Preferred stock redemption	(295,500)	(295,500)	(285,173)			(10,327)
Preferred stock redemption (in shares)			(11,820)
Issuance of common stock, net	761,070	763,508		19,096	744,412			(2,438)
Issuance of common stock, net (in shares)				19,096
Repurchase of common stock	(8,167)	(8,167)		(196)	(7,971)
Repurchase of common stock (in shares)				(196)
Exercise of stock options	51,509	51,509		2,451	49,058
Exercise of stock options (in shares)	2,451			2,451
Amortization of deferred compensation	16,947	16,947			16,947
Preferred dividends	(6,679)	(6,679)				(6,679)
Common dividends ($1.575 and $1.50 per share for the period ended September 30, 2013 and 2012, respectively)	(631,549)	(631,549)				(631,549)
Distributions to noncontrolling interests	(11,759)							(11,759)
Noncontrolling interests in acquisitions	27,432							27,432
Issuance of noncontrolling interests	826							826
Purchase of noncontrolling interests	(417)							(417)
Balance at Sep. 30, 2012	9,727,853	9,517,999		429,980	10,185,982	(1,081,317)	(16,646)	209,854
Balance (in shares) at Sep. 30, 2012				429,980
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net				979,000
Issuance of common stock, net (in shares)				22,000
Balance at Oct. 31, 2012
Balance at Dec. 31, 2012	10,753,777	10,551,237		453,191	11,180,066	(1,067,367)	(14,653)	202,540
Balance (in shares) at Dec. 31, 2012				453,191
Increase (Decrease) in Stockholders' Equity
Net income	687,367	677,742				677,742		9,625
Other comprehensive income (loss)	(1,226)	(1,226)					(1,226)
Issuance of common stock, net	77,509	80,506		1,859	78,647			(2,997)
Issuance of common stock, net (in shares)				1,859
Repurchase of common stock	(2,502)	(2,502)		(51)	(2,451)
Repurchase of common stock (in shares)				(51)
Exercise of stock options	17,497	17,497		875	16,622
Exercise of stock options (in shares)	875			875
Amortization of deferred compensation	33,833	33,833			33,833
Common dividends ($1.575 and $1.50 per share for the period ended September 30, 2013 and 2012, respectively)	(716,869)	(716,869)				(716,869)
Distributions to noncontrolling interests	(11,536)							(11,536)
Issuance of noncontrolling interests	12,387							12,387
Balance at Sep. 30, 2013	$ 10,850,237	$ 10,640,218		$ 455,874	$ 11,306,717	$ (1,106,494)	$ (15,879)	$ 210,019
Balance (in shares) at Sep. 30, 2013				455,874