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	8,101					6,402	6,402	29	1,670	1,699
Other comprehensive income (loss):
Other comprehensive income (loss) before reclassification	(18,808)				(17,505)		(17,505)	(79)	(1,224)	(1,303)
Amounts reclassified from accumulated other comprehensive loss	6,479				6,282		6,282	28	169	197
Deferred compensation plan, net	207		(1,488)	1,695			207
Restricted stock issued, net of amortization	10,964	2		10,962			10,964
Common stock issued for stock based compensation, net	(5,172)			(5,172)			(5,172)
Common stock issued under dividend reinvestment plan	1,138			1,138			1,138
Common stock issued, net of issuance costs	125,608	19		125,589			125,608
Contributions from partners	443								443	443
Issuance of exchangeable operating partnership units	1,275							1,275		1,275
Distributions to partners	(4,029)								(4,029)	(4,029)
Cash dividends declared - common stock/unit	(303,044)					(301,678)	(301,678)	(1,366)		(1,366)
Ending Balance at Sep. 30, 2020	6,113,123	1,697	(24,687)	7,789,142	(23,220)	(1,703,338)	6,039,594	35,987	37,542	73,529
Beginning 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,310					12,688	12,688	57	565	622
Other comprehensive income (loss):
Other comprehensive income (loss) before reclassification	(613)				(551)		(551)	(2)	(60)	(62)
Amounts reclassified from accumulated other comprehensive loss	2,570				2,466		2,466	11	93	104
Deferred compensation plan, net	207		(90)	297			207
Restricted stock issued, net of amortization	3,372			3,372			3,372
Common stock issued for stock based compensation, net	3			3			3
Common stock issued under dividend reinvestment plan	382			382			382
Common stock issued, net of issuance costs	(7)			(7)			(7)
Contributions from partners	312								312	312
Distributions to partners	(2,211)								(2,211)	(2,211)
Cash dividends declared - common stock/unit	(101,404)					(100,949)	(100,949)	(455)		(455)
Ending Balance at Sep. 30, 2020	6,113,123	1,697	(24,687)	7,789,142	(23,220)	(1,703,338)	6,039,594	35,987	37,542	73,529
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	297,305					293,552	293,552	1,315	2,438	3,753
Other comprehensive income (loss):
Other comprehensive income (loss) before reclassification	3,383				3,157		3,157	16	210	226
Amounts reclassified from accumulated other comprehensive loss	3,109				2,850		2,850	12	247	259
Deferred compensation plan, net	77		(882)	959			77
Restricted stock issued, net of amortization	9,468	2		9,466			9,468
Common stock issued for stock based compensation, net	(3,662)			(3,662)			(3,662)
Common stock issued under dividend reinvestment plan	1,172			1,172			1,172
Common stock issued, net of issuance costs	82,510	13		82,497			82,510
Common stock issued for partnership units exchanged				99			99	(99)		(99)
Distributions to partners	(3,272)								(3,272)	(3,272)
Cash dividends declared - common stock/unit	(304,773)					(303,414)	(303,414)	(1,359)		(1,359)
Ending Balance at Sep. 30, 2021	6,143,464	1,712	(25,318)	7,882,613	(12,618)	(1,775,668)	6,070,721	35,612	37,131	72,743
Beginning 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	118,848					117,406	117,406	519	923	1,442
Other comprehensive income (loss):
Other comprehensive income (loss) before reclassification	89				88		88	1		1
Amounts reclassified from accumulated other comprehensive loss	1,040				952		952	4	84	88
Deferred compensation plan, net	77		569	(492)			77
Restricted stock issued, net of amortization	3,425			3,425			3,425
Common stock issued for stock based compensation, net	80			80			80
Common stock issued under dividend reinvestment plan	404			404			404
Common stock issued, net of issuance costs	82,510	13		82,497			82,510
Distributions to partners	(1,283)								(1,283)	(1,283)
Cash dividends declared - common stock/unit	(101,757)					(101,301)	(101,301)	(456)		(456)
Ending Balance at Sep. 30, 2021	$ 6,143,464	$ 1,712	$ (25,318)	$ 7,882,613	$ (12,618)	$ (1,775,668)	$ 6,070,721	$ 35,612	$ 37,131	$ 72,743