CONSOLIDATED STATEMENTS OF EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS (USD $) In Thousands, except Share data, unless otherwise specified	Total	Redeemable Noncontrolling Interests	Total Stockholders' Equity	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Comprehensive Income
Balance at Dec. 31, 2009		$ 20,591
Balance at Dec. 31, 2009	2,128,466		1,857,571	967	2,227,931	(345,930)	(25,397)	270,895
Balance (in shares) at Dec. 31, 2009				96,667,689
Comprehensive income:
Net income	28,001		25,190			25,190		2,811	28,001
Net income		419
Interest rate swap/cap agreements	22,160		22,160				22,160		22,160
Total comprehensive income	50,161		47,350			25,190	22,160	2,811	50,161
Total comprehensive income		419
Amortization of share and unit-based plans	27,545		27,545	6	27,539
Amortization of share and unit-based plans (in shares)				628,009
Exercise of stock options	99		99		99
Exercise of stock options (in shares)				5,400
Exercise of stock warrants	(17,639)		(17,639)		(17,639)
Employee stock purchases	803		803		803
Employee stock purchases (in shares)				28,450
Stock offering, net	1,220,829		1,220,829	310	1,220,519
Stock offering, net (in shares)				31,000,000
Distributions paid ($2.23), ($2.05) and ($2.10) per share for the year ended 2012, 2011 and 2010, respectively	(243,617)		(243,617)			(243,617)
Distributions to noncontrolling interests	(26,908)							(26,908)
Distributions to noncontrolling interests		(419)
Stock dividend	43,086		43,086	14	43,072
Stock dividend (in shares)				1,449,542
Contributions from noncontrolling interests	5,159							5,159
Other	205		205		205
Conversion of noncontrolling interests to common shares			8,759	7	8,752			(8,759)
Conversion of noncontrolling interests to common shares (in shares)				672,942
Redemption of noncontrolling interests	(193)							(193)
Redemption of noncontrolling interests		(9,225)
Adjustment of noncontrolling interest in Operating Partnership			(54,712)		(54,712)			54,712
Balance at Dec. 31, 2010		11,366
Balance at Dec. 31, 2010	3,187,996		2,890,279	1,304	3,456,569	(564,357)	(3,237)	297,717
Balance (in shares) at Dec. 31, 2010				130,452,032
Comprehensive income:
Net income	168,910		156,866			156,866		12,044	168,910
Net income		165
Interest rate swap/cap agreements	3,237		3,237				3,237		3,237
Total comprehensive income	172,147		160,103			156,866	3,237	12,044	172,147
Total comprehensive income		165
Amortization of share and unit-based plans	18,519		18,519	6	18,513
Amortization of share and unit-based plans (in shares)				597,415
Exercise of stock options	266		266		266
Exercise of stock options (in shares)				10,800
Exercise of stock warrants	(1,278)		(1,278)		(1,278)
Employee stock purchases	766		766		766
Employee stock purchases (in shares)				17,285
Distributions paid ($2.23), ($2.05) and ($2.10) per share for the year ended 2012, 2011 and 2010, respectively	(271,140)		(271,140)			(271,140)
Distributions to noncontrolling interests	(25,643)							(25,643)
Distributions to noncontrolling interests		(165)
Contributions from noncontrolling interests	78,921							78,921
Other	4,139		4,139		4,139
Conversion of noncontrolling interests to common shares			21,698	11	21,687			(21,698)
Conversion of noncontrolling interests to common shares (in shares)				1,075,912
Redemption of noncontrolling interests	(42)		(26)		(26)			(16)
Redemption of noncontrolling interests		(11,366)
Adjustment of noncontrolling interest in Operating Partnership			(9,989)		(9,989)			9,989
Balance at Dec. 31, 2011	3,164,651		2,813,337	1,321	3,490,647	(678,631)		351,314
Balance (in shares) at Dec. 31, 2011	132,153,444			132,153,444
Comprehensive income:
Net income	366,389		337,426			337,426		28,963	366,389
Amortization of share and unit-based plans	14,970		14,970	6	14,964
Amortization of share and unit-based plans (in shares)				566,717
Exercise of stock options	307		307		307
Exercise of stock options (in shares)				10,800
Exercise of stock warrants	(7,371)		(7,371)		(7,371)
Employee stock purchases	956		956		956
Employee stock purchases (in shares)				20,372
Stock offering, net	175,649		175,649	30	175,619
Stock offering, net (in shares)				2,961,903
Stock issued to acquire property	30,000		30,000	5	29,995
Stock issued to acquire property (in shares)				535,265
Distributions paid ($2.23), ($2.05) and ($2.10) per share for the year ended 2012, 2011 and 2010, respectively	(298,536)		(298,536)			(298,536)
Distributions to noncontrolling interests	(30,694)							(30,694)
Contributions from noncontrolling interests	605							605
Other	(589)		(589)		(589)
Conversion of noncontrolling interests to common shares			26,991	13	26,978			(26,991)
Conversion of noncontrolling interests to common shares (in shares)				1,258,509
Redemption of noncontrolling interests	(86)		(58)		(58)			(28)
Adjustment of noncontrolling interest in Operating Partnership			(15,553)		(15,553)			15,553
Balance at Dec. 31, 2012	$ 3,416,251		$ 3,077,529	$ 1,375	$ 3,715,895	$ (639,741)		$ 338,722
Balance (in shares) at Dec. 31, 2012	137,507,010			137,507,010