CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Preferred Shares	Common Shares	Additional Paid-in-Capital	Accumulated Distributions in Excess of Net Income	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning Balance at Dec. 31, 2019	$ 1,724,719	$ 94,016	$ 25	$ 2,976,670	$ (1,363,676)	$ (1,928)	$ 19,612
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of partnership interest in real estate	1,285						1,285
Redemption of noncontrolling OP units for common shares				632			(632)
Issuance of common shares and deferred compensation amortization, net	230,117		3	230,114
Repurchase of common shares to settle tax obligations	(2,623)			(2,623)
Forfeiture of employee common shares	1				1
Dividends/distributions	(91,518)				(89,997)		(1,521)
Net income	81,169				78,924		2,245
Other comprehensive income	(17,759)					(17,759)
Repurchase of common shares	(11,042)			(11,042)
Ending Balance at Sep. 30, 2020	1,914,349	94,016	28	3,193,751	(1,374,748)	(19,687)	20,989
Beginning Balance at Jun. 30, 2020	1,892,186	94,016	28	3,185,458	(1,386,001)	(20,730)	19,415
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of partnership interest in real estate	398						398
Redemption of noncontrolling OP units for common shares				150			(150)
Issuance of common shares and deferred compensation amortization, net	8,143			8,143
Dividends/distributions	(31,039)				(30,651)		(388)
Net income	43,618				41,904		1,714
Other comprehensive income	1,043					1,043
Ending Balance at Sep. 30, 2020	1,914,349	94,016	28	3,193,751	(1,374,748)	(19,687)	20,989
Beginning Balance at Dec. 31, 2020	1,991,137	94,016	28	3,196,315	(1,301,726)	(17,963)	20,467
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of partnership interest in real estate	11,050						11,050
Redemption of noncontrolling OP units for common shares				670			(670)
Redemption of noncontrolling OP units for real estate	(22,305)			(12,919)			(9,386)
Issuance of common shares and deferred compensation amortization, net	60,469			60,469
Repurchase of common shares to settle tax obligations	(5,120)			(5,120)
Forfeiture of employee common shares	2				2
Dividends/distributions	(96,263)				(94,768)		(1,495)
Net income	122,320				120,358		1,962
Other comprehensive income	7,072					7,072
Reallocation of noncontrolling interests				435			(435)
Ending Balance at Sep. 30, 2021	2,068,362	94,016	28	3,239,850	(1,276,134)	(10,891)	21,493
Beginning Balance at Jun. 30, 2021	2,051,369	94,016	28	3,195,040	(1,250,735)	(12,041)	25,061
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of partnership interest in real estate	5,965						5,965
Redemption of noncontrolling OP units for common shares				202			(202)
Redemption of noncontrolling OP units for real estate	(22,305)			(12,919)			(9,386)
Issuance of common shares and deferred compensation amortization, net	57,527			57,527
Dividends/distributions	(32,402)				(32,037)		(365)
Net income	7,058				6,638		420
Other comprehensive income	1,150					1,150
Ending Balance at Sep. 30, 2021	$ 2,068,362	$ 94,016	$ 28	$ 3,239,850	$ (1,276,134)	$ (10,891)	$ 21,493