Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common stock	Additional Paid-in Capital	Accumulated Dividends in Excess of Earnings	Accumulated Other Comprehensive Income (Loss), net	Total Stockholders’ Equity	Noncontrolling Interests in Operating Partnership	Noncontrolling Interests in Consolidated Joint Ventures	Total Noncontrolling Interests
Balance at Dec. 31, 2012	$ 3,498,384	$ 572,711	$ 1,247	$ 3,562,642	$ (656,104)	$ (12,191)	$ 3,468,305	$ 24,135	$ 5,944	$ 30,079
Balance (shares) at Dec. 31, 2012			125,140,783
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 1	630			631	(631)		(631)
Conversion of units to common stock (shares)			57,138
Issuance of restricted stock, net of forfeitures (shares)			112,245
Net proceeds from sale of common stock	(504)			(504)			(504)
Exercise of stock options	230			230			230
Exercise of stock options (shares)			5,569
Issuance of preferred stock, net of offering costs	241,468	241,468					241,468
Conversion of preferred stock (shares)			3,139,615
Conversion of preferred stock		(119,348)	$ 31	119,317
Amortization of unearned compensation on 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	(410,028)				(400,701)		(400,701)	(9,327)		(9,327)
Contributions from noncontrolling interests in consolidated joint ventures	430								430	430
Net income	320,449				314,488		314,488	5,366	595	5,961
Other comprehensive income— foreign currency translation adjustments	14,636					14,321	14,321	315		315
Other comprehensive income— fair value of interest rate swaps	2,473					2,423	2,423	50		50
Other comprehensive income—reclassification of accumulated other comprehensive loss to interest expense	6,258					6,138	6,138	120		120
Balance (shares) at Dec. 31, 2013			128,455,350
Balance at Dec. 31, 2013	3,646,512	694,831	$ 1,279	3,688,937	(785,222)	10,691	3,610,516	29,027	6,969	35,996
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 1	1,654			1,655	(1,655)		(1,655)
Conversion of units to common stock (shares)			134,073
Issuance of restricted stock, net of forfeitures (shares)			124,163
Common stock offering costs	(625)			(625)			(625)
Exercise of stock options	711			711			711
Exercise of stock options (shares)			42,757
Issuance of common stock in exchange for cash and debentures (shares/units)			6,869,912
Issuance of common stock in exchange for cash	266,400		$ 69	266,331			266,400
Conversion of preferred stock	353,290	353,290					353,290
Amortization of unearned compensation on share-based awards	23,737			23,737			23,737
Reclassification of vested share-based awards				(10,306)			(10,306)	10,306		10,306
Dividends declared on preferred stock	(67,465)				(67,465)		(67,465)
Dividends and distributions on common stock and common and incentive units	(454,204)				(444,103)		(444,103)	(10,101)		(10,101)
Distributions to noncontrolling interests in consolidated joint ventures, net of contributions	(643)								(643)	(643)
Net income	203,415				200,183		200,183	2,767	465	3,232
Other comprehensive income— foreign currency translation adjustments	(52,373)					(51,312)	(51,312)	(1,061)		(1,061)
Other comprehensive income— fair value of interest rate swaps	(7,936)					(7,775)	(7,775)	(161)		(161)
Other comprehensive income—reclassification of accumulated other comprehensive loss to interest expense	3,419					3,350	3,350	69		69
Balance (shares) at Dec. 31, 2014			135,626,255
Balance at Dec. 31, 2014	3,914,238	1,048,121	$ 1,349	3,970,439	(1,096,607)	(45,046)	3,878,256	29,191	6,791	35,982
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 2	1,841			1,843	(1,843)		(1,843)
Conversion of units to common stock (shares)			156,008
Issuance of restricted stock, net of forfeitures (shares)			72,673
Common stock offering costs	799			799			799
Exercise of stock options	$ 896			896			896
Exercise of stock options (shares)	29,311		29,311
Issuance of common stock in exchange for cash and debentures (shares/units)			10,500,000
Issuance of common stock in exchange for cash	$ 675,577		$ 105	675,472			675,577
Issuance of preferred stock, net of offering costs	242,014	242,014					242,014
Amortization of unearned compensation on share-based awards	14,375			14,375			14,375
Reclassification of vested share-based awards				(8,602)			(8,602)	8,602		8,602
Dividends declared on preferred stock	(79,423)				(79,423)		(79,423)
Dividends and distributions on common stock and common and incentive units	(480,541)				(470,748)		(470,748)	(9,793)		(9,793)
Distributions to noncontrolling interests in consolidated joint ventures, net of contributions	(493)								(493)	(493)
Net income	301,591				296,689		296,689	4,442	460	4,902
Other comprehensive income— foreign currency translation adjustments	(51,745)					(50,775)	(50,775)	(970)		(970)
Other comprehensive income— fair value of interest rate swaps	(3,407)					(3,338)	(3,338)	(69)		(69)
Other comprehensive income—reclassification of accumulated other comprehensive loss to interest expense	2,621					2,569	2,569	52		52
Balance (shares) at Dec. 31, 2015			146,384,247
Balance at Dec. 31, 2015	$ 4,536,502	$ 1,290,135	$ 1,456	$ 4,655,220	$ (1,350,089)	$ (96,590)	$ 4,500,132	$ 29,612	$ 6,758	$ 36,370