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)	Noncontrolling Interests
Balance at Dec. 31, 2009	$ 5,958,609	$ 5,780,537	$ 285,173	$ 293,548	$ 5,719,400	$ (515,450)	$ (2,134)	$ 178,072
Balance (in shares) at Dec. 31, 2009			11,820	293,548
Increase (Decrease) in Stockholders' Equity
Net income	344,395	330,709				330,709		13,686
Other comprehensive income (losses)	(11,103)	(11,103)					(11,103)
Issuance of common stock, net	2,425,110	2,431,245		77,278	2,353,967			(6,135)
Issuance of common stock, net (in shares)				77,278
Repurchase of common stock	(4,527)	(4,527)		(154)	(4,373)
Repurchase of common stock (in shares)				(154)
Exercise of stock options	6,317	6,317		253	6,064
Exercise of stock options (in shares)				253
Amortization of deferred compensation	14,924	14,924			14,924
Preferred dividends	(21,130)	(21,130)				(21,130)
Common dividends ($2.00, $1.92 and $1.86 per share for the year ended 2012, 2011 and 2010, respectively)	(569,605)	(569,605)				(569,605)
Distributions to noncontrolling interests	(16,049)							(16,049)
Noncontrolling interests in acquisitions	10,002							10,002
Issuance of noncontrolling interests	8,395							8,395
Other	709							709
Balance at Dec. 31, 2010	8,146,047	7,957,367	285,173	370,925	8,089,982	(775,476)	(13,237)	188,680
Balance (in shares) at Dec. 31, 2010			11,820	370,925
Increase (Decrease) in Stockholders' Equity
Net income	554,494	538,891				538,891		15,603
Other comprehensive income (losses)	(6,345)	(6,345)					(6,345)
Issuance of common stock, net	1,302,008	1,305,464		36,683	1,268,781			(3,456)
Issuance of common stock, net (in shares)				36,683
Repurchase of common stock	(4,991)	(4,991)		(136)	(4,855)
Repurchase of common stock (in shares)				(136)
Exercise of stock options	30,796	30,796		1,157	29,639
Exercise of stock options (in shares)	1,157			1,157
Amortization of deferred compensation	20,034	20,034			20,034
Preferred dividends	(21,130)	(21,130)				(21,130)
Common dividends ($2.00, $1.92 and $1.86 per share for the year ended 2012, 2011 and 2010, respectively)	(766,559)	(766,559)				(766,559)
Distributions to noncontrolling interests	(15,156)							(15,156)
Noncontrolling interests in acquisitions	1,500							1,500
Issuance of noncontrolling interests	14,028							14,028
Purchase of noncontrolling interests	(34,104)	(20,045)			(20,045)			(14,059)
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	846,842	832,540				832,540		14,302
Other comprehensive income (losses)	4,929	4,929					4,929
Preferred stock redemption	(295,500)	(295,500)	(285,173)			(10,327)
Preferred stock redemption (in shares)			11,820
Issuance of common stock, net	1,756,796	1,781,825		42,468	1,739,357			(25,029)
Issuance of common stock, net (in shares)				42,468
Repurchase of common stock	(15,632)	(15,632)		(361)	(15,271)
Repurchase of common stock (in shares)				(361)
Exercise of stock options	51,622	51,622		2,455	49,167
Exercise of stock options (in shares)	2,455			2,455
Amortization of deferred compensation	23,277	23,277			23,277
Preferred dividends	(6,679)	(6,679)				(6,679)
Common dividends ($2.00, $1.92 and $1.86 per share for the year ended 2012, 2011 and 2010, respectively)	(858,627)	(858,627)				(858,627)
Distributions to noncontrolling interests	(15,631)							(15,631)
Noncontrolling interests in acquisitions	42,734							42,734
Issuance of noncontrolling interests	1,584							1,584
Purchase of noncontrolling interests	(2,560)							(2,560)
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