Consolidated Statement of Changes in Equity - USD ($) $ in Thousands	Parent Company [Member]	Partnership Interest [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]	Noncontrolling Interest [Member] Parent Company [Member]	Common 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]	Partners Capital Total [Member] Partnership Interest [Member]	Noncontrolling Interest [Member] Partnership Interest [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Partnership Interest [Member]	Limited Partner [Member] Partnership Interest [Member]	General Partner [Member] Partnership Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	$ 6,763,957		$ 1,714	$ (18,307)	$ 7,873,104		$ (6,277)	$ (1,127,281)	$ 6,722,953	$ 10,907	$ 30,097	$ 41,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	30,903	$ 30,903	0	0	0	$ 12	12	30,889	30,901	0	2	2											$ 30,901	$ 2	$ 12	$ 0	$ 30,889
Partners' Capital, Adjusted Balance		6,763,957																					6,733,860	30,097	(6,277)	10,907	6,729,230
Beginning balance at Dec. 31, 2017	6,733,054		1,714	(18,307)	7,873,104		(6,289)	(1,158,170)	6,692,052	10,907	30,095	41,002
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	52,660
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	53,465	53,465	0	0	0		0		52,660	111	694	805											52,771	694	0	111	52,660
Current period other comprehensive income, net	11,524	11,524	0	0	0	11,041	11,041	0	11,041	23	460												11,064		11,041	23	0
Other comprehensive (loss) income attributable to noncontrolling interests	483	460																						460
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition	(3)		0	(449)	446		0	0	(3)	0	0	0
Restricted stock issued, net of amortization	4,121	4,121	1	0	4,120		0	0	4,121	0	0	0											4,121	0	0	0	4,121
Common stock redeemed for taxes withheld for stock based compensation, net													$ 6,643	$ 0	$ 0	$ 6,643	$ 0	$ 0	$ 6,643	$ 0	$ 0	$ 0
Stock Repurchased and Retired During Period, Value													(124,989)	(21)	0	(124,968)	0	0	(124,989)	0		0
Common stock issued under dividend reinvestment plan	358	358											358	0	0	358	0	0	358	0	0	0
Common stock issued, net of issuance costs													10	0	0	10	0	0	10	0	0	0
Distributions to partners	(1,018)	(96,419)	0	0	0		0	0	0	0	(1,018)	(1,018)											(95,401)	(1,018)	0	(194)	(95,207)
Common units repurchased and retired as a result of common stock repurchased and retired by Parent Company		(124,989)																					(124,989)	0	0	0	(124,989)
Cash dividends declared - common stock/unit	95,401		0	0	0		0	95,207	95,207	194	0	194
Ending Balance at Mar. 31, 2018	6,605,381		1,694	(18,756)	7,746,427		4,764	(1,169,828)	6,564,301	10,847	30,233	41,080
Beginning balance at Dec. 31, 2018	6,450,168		1,679	(19,834)	7,672,517		(927)	(1,255,465)	6,397,970	10,666	41,532	52,198
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	90,446
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	91,493	91,493	0	0	0		0		90,446	190	857	1,047											90,636	857	0	190	90,446
Current period other comprehensive income, net	(5,528)	(5,528)	0	0	0	$ (5,169)	(5,169)	0	(5,169)	(11)	(348)												(5,180)		(5,169)	(11)	0
Other comprehensive (loss) income attributable to noncontrolling interests	(359)	(348)																						(348)
Adjustments to Additional Paid in Capital, Share-based Compensation, Other Long-term Incentive Plans, Requisite Service Period Recognition	0		0	(1,392)	1,392		0	0	0	0	0	0
Restricted stock issued, net of amortization	3,952	3,952	2	0	3,950		0	0	3,952	0	0	0											3,952	0	0	0	3,952
Common stock redeemed for taxes withheld for stock based compensation, net													6,051	0	0	6,051	0	0	6,051	0	0	0
Stock Repurchased and Retired During Period, Value													(32,778)	(6)	0	(32,772)	0	0	(32,778)	0	0	0
Common stock issued under dividend reinvestment plan	383	383											$ 383	$ 0	$ 0	$ 383	$ 0	$ 0	$ 383	$ 0	$ 0	$ 0
Contributions from partners	895	895	0	0	0		0	0	0	0	895	895											0	895	0	0	0
Distributions to partners	(1,565)	(99,761)	0	0	0		0	0	0	0	(1,565)	(1,565)											(98,196)	(1,565)	0	(204)	(97,992)
Common units issued as a result of common stock issued by Parent Company, net of repurchases		5,668																					5,668	0	0	0	5,668
Common units repurchased and retired as a result of common stock repurchased and retired by Parent Company		(32,778)																					(32,778)	0	0	0	(32,778)
Cash dividends declared - common stock/unit	98,196		0	0	0		0	97,992	97,992	204	0	204
Ending Balance at Mar. 31, 2019	6,402,773		1,675	(21,226)	7,639,353		(6,096)	(1,263,011)	6,350,695	10,641	41,437	52,078
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Partners' Capital Account, Redemptions	$ 0	$ 0	$ 0	$ 0	$ (66)		$ 0	$ 0	$ (66)	$ 0	$ 66	$ 66											$ (66)	$ 66	$ 0	$ 0	$ (66)