Consolidated Statement of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interests	Series C Preferred Stock	Series D Preferred Stock	Series I Preferred Stock
Balance at Dec. 31, 2011	$ 6,453,309	$ 892	$ 4,236,959	$ (308,708)	$ (28,445)	$ 1,704,506	$ 477,762	$ 274,022	$ 96,321
Balance (in shares) at Dec. 31, 2011		85,783,000
Increase (Decrease) in Stockholders' Equity
Net income after allocation to noncontrolling interests in SLGOP and preferred stock redemption costs	165,824					159,032	6,792
Comprehensive Income:	(836)				(836)
Preferred dividends	(23,004)					(23,004)
Redemption of units and DRIP proceeds	117,022	15	117,007
Redemption of units and DRIP proceeds (in shares)		1,523,000
Redemption of preferred stock	(190,003)							(93,682)	(96,321)
Reallocation of noncontrolling interest in the Operating Partnership	(44,893)					(44,893)
Deferred compensation plan & stock award, net	(10,566)	2	629	(11,197)
Deferred compensation plan & stock award, net (in shares)		66,000
Amortization of deferred compensation plan	20,667		20,667
Proceeds from issuance of preferred stock	222,245									222,245
Proceeds from issuance of common stock	201,299	27	201,272
Proceeds from issuance of common stock (in shares)		2,640,000
Proceeds from stock options exercised	12,893	4	12,889
Proceeds from stock options exercised (in shares)		351,000
Consolidation of joint venture interest	19,181						19,181
Cash distributions to noncontrolling interests	(15,622)						(15,622)
Cash distribution declared ($0.75 per common share, none of which represented a return of capital for federal income tax purposes)	(67,491)					(67,491)
Balance at Sep. 30, 2012	$ 6,860,025	$ 940	$ 4,589,423	$ (319,905)	$ (29,281)	$ 1,728,150	$ 488,113	$ 180,340		$ 222,245
Balance (in shares) at Sep. 30, 2012	90,363,063	90,363,000