Consolidated Statement of Changes in Equity - USD ($) $ in Thousands	Total	Parent Company [Member]	Partnership Interest [Member]	Preferred Stock [Member] Parent Company [Member]	Common Stock [Member] Parent Company [Member]	Treasury Stock [Member] Parent Company [Member]	Additional Paid-in Capital [Member] Parent Company [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Parent Company [Member]	Distributions in Excess of Net Income [Member] Parent Company [Member]	Total Stockholders' Equity [Member] Parent Company [Member]	Noncontrolling Interest Exchangeable Operating Partnership Units [Member] Parent Company [Member]	Noncontrolling Interests in Limited Partners' Interest in Consolidated Partnerships [Member] Parent Company [Member]	Total Noncontrolling Interests [Member] Parent Company [Member]	Noncontrolling Interest [Member] Parent Company [Member]	Common Stock [Member] Parent Company [Member]	Common Stock [Member] Preferred Stock [Member] Parent Company [Member]	Common Stock [Member] Common Stock [Member] Parent Company [Member]	Common Stock [Member] Treasury Stock [Member] Parent Company [Member]	Common Stock [Member] Additional Paid-in Capital [Member] Parent Company [Member]	Common Stock [Member] Accumulated Other Comprehensive Income (Loss) [Member] Parent Company [Member]	Common Stock [Member] Distributions in Excess of Net Income [Member] Parent Company [Member]	Common Stock [Member] Total Stockholders' Equity [Member] Parent Company [Member]	Common Stock [Member] Noncontrolling Interest Exchangeable Operating Partnership Units [Member] Parent Company [Member]	Common Stock [Member] Noncontrolling Interests in Limited Partners' Interest in Consolidated Partnerships [Member] Parent Company [Member]	Common Stock [Member] Noncontrolling Interest [Member] Parent Company [Member]	Noncontrolling Interest [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Limited Partner [Member]	General Partner [Member]
Beginning balance at Dec. 31, 2015	$ 2,082,620	$ 2,082,620		$ 325,000	$ 972	$ (19,658)	$ 2,742,508		$ (58,693)	$ (936,020)	$ 2,054,109	$ (1,975)	$ 30,486		$ 28,511												$ 30,486	$ (58,693)	$ (1,975)	$ 2,112,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	53,577	53,577	$ 53,577	0	0	0	0		0		53,143	85	349		434												349	0	85	53,143
Net Income (Loss) Attributable to Parent		53,143	53,228
Current period other comprehensive income, net	(14,368)	(14,368)	(14,368)	0	0	0	0	$ (14,200)	(14,200)	0	(14,200)	(22)	(146)															(14,200)	(22)	0
Other comprehensive income (loss) attributable to noncontrolling interests		(168)	(146)																								(146)
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition		0		0	0	1,287	(1,287)		0	0	0	0	0		0
Restricted stock issued, net of amortization	3,402	3,402		0	2	0	3,400		0	0	3,402	0	0		0												0	0	0	3,402
Common stock redeemed for taxes withheld for stock based compensation, net																$ 7,950	$ 0	$ 0	$ 0	$ 7,950	$ 0	$ 0	$ 7,950	$ 0	$ 0	$ 0
Common stock issued under dividend reinvestment plan		292	292														0	0	0	292	0	0	292	0	0	0
Common stock issued, net of issuance costs		12,293		0	2	0	12,291		0	0	12,293	0	0		0
Contributions from partners	8,389	8,389		0	0	0	0		0	0	0	0	8,389		8,389												8,389	0	0	0
Distributions to partners	(50,616)	(1,737)		0	0	0	(350)		0	0	(350)	0	(1,387)		(1,387)												(1,387)	0	(77)	49,152
Common units redeemed as a result of common stock redeemed by Parent Company, net of issuances	(4,635)																										0	0	0	(4,635)
Cash dividends declared: preferred stock/unit	5,266	5,266		0	0	0	0		0	5,266	5,266	0	0		0												0	0	0	5,266
Preferred stock		(5,266)
Cash dividends declared - common stock/unit		48,879		0	0	0	0		0	48,802	48,802	77	0		77
Ending Balance at Mar. 31, 2016	2,082,373	2,082,373		325,000	976	(18,371)	2,748,904		(72,893)	(936,945)	2,046,671	(1,989)	37,691		35,702												37,691	(72,893)	(1,989)	2,119,564
Beginning balance at Dec. 31, 2016	2,624,502	2,624,502		325,000	1,045	(17,062)	3,294,923		(18,346)	(994,259)	2,591,301	(1,967)	35,168		33,201												35,168	(18,346)	(1,967)	2,609,647
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(20,715)	(20,715)	(20,715)	0	0	0	0		0		(21,367)	(19)	671		652												671	0	(19)	(21,367)
Net Income (Loss) Attributable to Parent		(21,367)	(21,386)
Current period other comprehensive income, net	2,620	2,618	2,618	0	0	0	0	$ 2,554	2,555	0	2,555	2	63															2,555	2	0
Other comprehensive income (loss) attributable to noncontrolling interests		65	63																								63
Other Comprehensive Income, Net of Tax		2,620
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition		1		0	0	(411)	412		0	0	1	0	0		0
Restricted stock issued, net of amortization	3,733	3,733		0	2	0	3,731		0	0	3,733	0	0		0												0	0	0	3,733
Common stock redeemed for taxes withheld for stock based compensation, net																18,220	0	1	0	18,219	0	0	18,220	0	0	0
Common stock issued under dividend reinvestment plan		301	$ 301														0	0	0	301	0	0	301	0	0	0
Common stock issued, net of issuance costs																$ 4,479,686	$ 0	$ 655	$ 0	$ 4,479,031	$ 0	$ 0	$ 4,479,686	$ 0	$ 0	$ 0
Contributions from partners	153	153		0	0	0	0		0	0	0	0	153		153												153	0	0	0
Distributions to partners	(54,317)	(838)		0	0	0	0		0	0	0	0	(838)		(838)												(838)	0	(79)	(53,400)
Common units redeemed as a result of common stock redeemed by Parent Company, net of issuances	(4,461,767)																										0	0	0	(4,461,767)
Cash dividends declared: preferred stock/unit	3,241	3,241		0	0	0	0		0		3,241	0	0		0												0	0	0	3,241
Redemption of preferred stock		250,000		250,000	0	0	(8,615)		0	8,615	250,000	0	0	$ 0
Preferred stock		(11,856)								(3,241)
Cash dividends declared - common stock/unit		53,479		0	0	0	0		0	53,400	53,400	79	0		79
Ending Balance at Mar. 31, 2017	$ 6,764,503	$ 6,764,503		$ 75,000	$ 1,701	$ (17,473)	$ 7,768,794		$ (15,791)	$ (1,080,882)	$ 6,731,349	$ (2,063)	$ 35,217		$ 33,154												$ 35,217	$ (15,791)	$ (2,063)	$ 6,747,139