Consolidated Statements Of Equity (USD $) In Thousands, except Share data	Total Stockholders' Equity [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Dividends In Excess Of Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Noncontrolling Interests In Operating Partnership [Member]	Noncontrolling Interests In Consolidated Joint Ventures [Member]	Total Noncontrolling Interests [Member]	Total
Balance at Dec. 31, 2010	$ 1,962,518	$ 502,341	$ 909	$ 1,849,497	$ (348,148)	$ (42,081)	$ 52,436	$ 39,709	$ 92,145	$ 2,054,663
Balance (shares) at Dec. 31, 2010			91,159,221
Conversion of units to common stock	7,508		8	7,500			(7,508)		(7,508)
Conversion of units to common stock (shares)			658,723
Issuance of restricted stock, net of forfeitures (shares)			79,119
Net proceeds from sale of common stock	455,580		77	455,503						455,580
Net proceeds from sale of common stock (shares)			7,746,886
Exercise of stock options	4,805		1	4,804						4,805
Exercise of stock options (shares)			123,777
Issuance of common stock in exchange for debentures	(11,450)		11	(11,461)						(11,450)
Issuance of common stock in exchange for debentures (shares/units)			1,087,820
Issuance of preferred stock, net of offering costs	277,292	277,292								277,292
Conversion of preferred stock		(209,852)	51	209,801
Conversion of preferred stock (shares)			5,183,733
Amortization of unearned compensation regarding share based awards	16,199			16,199						16,199
Reclassification of vested share based awards	(8,472)			(8,472)			8,472		8,472
Dividends declared on preferred stock	(25,397)				(25,397)					(25,397)
Dividends and distributions on common stock and common and incentive units	(271,412)				(271,412)		(14,120)		(14,120)	(285,532)
Distributions to noncontrolling interests in consolidated joint ventures								(428)	(428)	(428)
Purchase of noncontrolling interests in consolidated joint venture	(26,720)			(26,720)				(26,520)	(26,520)	(53,240)
Net income	156,265				156,265		6,185	(324)	5,861	162,126
Other comprehensive income - foreign currency translation adjustments	(16,123)					(16,123)	(530)		(530)	(16,653)
Other comprehensive income - fair value of interest rate swaps	(3,050)					(3,050)	(135)		(135)	(3,185)
Other comprehensive income - reclassification of accumulated other comprehensive loss to interest expense	5,374					5,374	257		257	5,631
Balance at Dec. 31, 2011	2,522,917	569,781	1,057	2,496,651	(488,692)	(55,880)	45,057	12,437	57,494	2,580,411
Balance (shares) at Dec. 31, 2011			106,039,279
Conversion of units to common stock	23,757		22	23,735			(23,757)		(23,757)
Conversion of units to common stock (shares)			2,234,860
Issuance of restricted stock, net of forfeitures (shares)			94,709
Net proceeds from sale of common stock	859,727		125	859,602						859,727
Net proceeds from sale of common stock (shares)			12,456,818
Exercise of stock options	4,195		2	4,193						4,195
Exercise of stock options (shares)			208,200
Issuance of preferred stock, net of offering costs	176,071	176,071								176,071
Conversion of preferred stock		(173,141)	41	173,100
Conversion of preferred stock (shares)			4,106,917
Amortization of unearned compensation regarding share based awards	15,938			15,938						15,938
Reclassification of vested share based awards	(8,544)			(8,544)			8,544		8,544
Dividends declared on preferred stock	(38,672)				(38,672)					(38,672)
Dividends and distributions on common stock and common and incentive units	(339,074)				(339,074)		(13,334)		(13,334)	(352,408)
Contributions from noncontrolling interests in consolidated joint ventures								4,302	4,302	4,302
Purchase of noncontrolling interests in consolidated joint venture	(2,033)			(2,033)				(10,351)	(10,351)	(12,384)
Net income	210,334				210,334		6,157	(444)	5,713	216,047
Other comprehensive income - foreign currency translation adjustments	46,722					46,722	1,581		1,581	48,303
Other comprehensive income - fair value of interest rate swaps	(7,426)					(7,426)	(267)		(267)	(7,693)
Other comprehensive income - reclassification of accumulated other comprehensive loss to interest expense	4,393					4,393	154		154	4,547
Balance at Dec. 31, 2012	3,468,305	572,711	1,247	3,562,642	(656,104)	(12,191)	24,135	5,944	30,079	3,498,384
Balance (shares) at Dec. 31, 2012			125,140,783
Conversion of units to common stock	631		1	630			(631)		(631)
Conversion of units to common stock (shares)			57,138
Issuance of restricted stock, net of forfeitures (shares)			112,245
Common stock offering costs	(504)			(504)						(504)
Exercise of stock options	230			230						230
Exercise of stock options (shares)			5,569							5,569
Issuance of preferred stock, net of offering costs	241,468	241,468								241,468
Conversion of preferred stock		(119,348)	31	119,317
Conversion of preferred stock (shares)			3,139,615
Amortization of unearned compensation regarding share based awards	15,621			15,621						15,621
Reclassification of vested share based awards	(8,999)			(8,999)			8,999		8,999
Dividends declared on preferred stock	(42,905)				(42,905)					(42,905)
Dividends and distributions on common stock and common and incentive units	(400,701)				(400,701)		(9,327)		(9,327)	(410,028)
Contributions from noncontrolling interests in consolidated joint ventures								430	430	430
Net income	314,488				314,488		5,366	595	5,961	320,449
Other comprehensive income - foreign currency translation adjustments	14,321					14,321	315		315	14,636
Other comprehensive income - fair value of interest rate swaps	2,423					2,423	50		50	2,473
Other comprehensive income - reclassification of accumulated other comprehensive loss to interest expense	6,138					6,138	120		120	6,258
Balance at Dec. 31, 2013	$ 3,610,516	$ 694,831	$ 1,279	$ 3,688,937	$ (785,222)	$ 10,691	$ 29,027	$ 6,969	$ 35,996	$ 3,646,512
Balance (shares) at Dec. 31, 2013			128,455,350