Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock	Additional Paid-in Capital	AOCI Attributable to Parent	Accumulated Distributions in Excess of Net Income	Parent	Noncontrolling Interest Exchangeable Operating Partnership Units	Noncontrolling Interests In Limited Partners Interest In Consolidated Partnerships	Noncontrolling Interest
Beginning Balance at Dec. 31, 2019	$ 6,289,961	$ 1,676	$ (23,199)	$ 7,654,930	$ (11,997)	$ (1,408,062)	$ 6,213,348	$ 36,100	$ 40,513	$ 76,613
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(5,209)					(6,286)	(6,286)	(28)	1,105	1,077
Other comprehensive income (loss) before reclassification	(18,195)				(16,954)		(16,954)	(77)	(1,164)	(1,241)
Amounts reclassified from accumulated other comprehensive loss	3,909				3,816		3,816	17	76	93
Deferred compensation plan, net			(1,398)	1,398
Restricted stock issued, net of amortization	7,592	2		7,590			7,592
Common stock issued under dividend reinvestment plan	756			756			756
Common stock issued, net of issuance costs	125,615	19		125,596			125,615
Contributions from partners	131								131	131
Distributions to partners	(1,818)								(1,818)	(1,818)
Cash dividends declared - common stock/unit	(201,640)					(200,729)	(200,729)	(911)		(911)
Common stock issued for stock based compensation, net	(5,175)			(5,175)			(5,175)
Issuance of exchangeable operating partnership units	1,275							1,275		1,275
Common stock issued for stock based compensation, net	(5,175)			(5,175)			(5,175)
Ending Balance at Jun. 30, 2020	6,197,202	1,697	(24,597)	7,785,095	(25,135)	(1,615,077)	6,121,983	36,376	38,843	75,219
Beginning Balance at Mar. 31, 2020	6,275,235	1,696	(23,897)	7,780,336	(25,531)	(1,533,182)	6,199,422	36,744	39,069	75,813
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	19,574					19,046	19,046	87	441	528
Other comprehensive income (loss) before reclassification	(2,131)				(2,016)		(2,016)	(10)	(105)	(115)
Amounts reclassified from accumulated other comprehensive loss	2,484				2,412		2,412	11	61	72
Deferred compensation plan, net			(700)	700
Restricted stock issued, net of amortization	3,828	1		3,827			3,828
Common stock issued under dividend reinvestment plan	377			377			377
Common stock issued, net of issuance costs	(158)			(158)			(158)
Contributions from partners	31								31	31
Distributions to partners	(654)								(654)	(654)
Cash dividends declared - common stock/unit	(101,397)					(100,941)	(100,941)	(456)		(456)
Common stock issued for stock based compensation, net	13			13			13
Common stock issued for stock based compensation, net	13			13			13
Ending Balance at Jun. 30, 2020	6,197,202	1,697	(24,597)	7,785,095	(25,135)	(1,615,077)	6,121,983	36,376	38,843	75,219
Beginning Balance at Dec. 31, 2020	6,058,147	1,697	(24,436)	7,792,082	(18,625)	(1,765,806)	5,984,912	35,727	37,508	73,235
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	178,457					176,146	176,146	796	1,515	2,311
Other comprehensive income (loss) before reclassification	3,294				3,069		3,069	15	210	225
Amounts reclassified from accumulated other comprehensive loss	2,069				1,898		1,898	8	163	171
Deferred compensation plan, net			(1,451)	1,451
Restricted stock issued, net of amortization	6,043	2		6,041			6,043
Common stock issued under dividend reinvestment plan	768			768			768
Common stock issued for partnership units exchanged				99			99	(99)		(99)
Distributions to partners	(1,989)								(1,989)	(1,989)
Cash dividends declared - common stock/unit	(203,016)					(202,113)	(202,113)	(903)		(903)
Common stock issued for stock based compensation, net	(3,742)			(3,742)			(3,742)
Common stock issued for partnership units exchanged				99			99	(99)		(99)
Common stock issued for stock based compensation, net	(3,742)			(3,742)			(3,742)
Ending Balance at Jun. 30, 2021	6,040,031	1,699	(25,887)	7,796,699	(13,658)	(1,791,773)	5,967,080	35,544	37,407	72,951
Beginning Balance at Mar. 31, 2021	6,043,044	1,698	(24,775)	7,791,416	(12,512)	(1,786,196)	5,969,631	35,667	37,746	73,413
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	96,832					95,490	95,490	432	910	1,342
Other comprehensive income (loss) before reclassification	(2,231)				(2,093)		(2,093)	(10)	(128)	(138)
Amounts reclassified from accumulated other comprehensive loss	1,034				947		947	4	83	87
Deferred compensation plan, net			(1,112)	1,112
Restricted stock issued, net of amortization	3,564	1		3,563			3,564
Common stock issued under dividend reinvestment plan	392			392			392
Common stock issued for partnership units exchanged				99			99	(99)		(99)
Distributions to partners	(1,204)								(1,204)	(1,204)
Cash dividends declared - common stock/unit	(101,517)					(101,067)	(101,067)	(450)		(450)
Common stock issued for stock based compensation, net	117			117			117
Common stock issued for partnership units exchanged				99			99	(99)		(99)
Common stock issued for stock based compensation, net	117			117			117
Ending Balance at Jun. 30, 2021	$ 6,040,031	$ 1,699	$ (25,887)	$ 7,796,699	$ (13,658)	$ (1,791,773)	$ 5,967,080	$ 35,544	$ 37,407	$ 72,951