CONDENSED CONSOLIDATED STATEMENT 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, 2018	$ 1,346,678	$ 94,016	$ 24	$ 2,772,855	$ (1,537,100)	$ 76	$ 16,807
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of noncontrolling OP units for common shares				161			(161)
Issuance of common shares and deferred compensation amortization, net	3,096			3,096
Repurchase of common shares	(958)			(958)
Repurchase of common shares to settle tax obligations	(3,942)		(1)	(3,941)
Forfeiture of employee common shares	5				5
Dividends/distributions	(52,678)				(51,017)		(1,661)
Net income	52,049				51,360		689
Other comprehensive loss	(76)					(76)
Ending Balance at Jun. 30, 2019	1,344,174	94,016	23	2,771,213	(1,536,752)	0	15,674
Beginning Balance at Mar. 31, 2019	1,345,334	94,016	23	2,769,822	(1,534,539)		16,012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of noncontrolling OP units for common shares				5			(5)
Issuance of common shares and deferred compensation amortization, net	1,386		0	1,386
Dividends/distributions	(26,315)				(25,546)		(769)
Net income	23,769				23,333		436
Other comprehensive loss	0
Ending Balance at Jun. 30, 2019	1,344,174	94,016	23	2,771,213	(1,536,752)	0	15,674
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	887						887
Redemption of noncontrolling OP units for common shares				482			(482)
Issuance of common shares and deferred compensation amortization, net	221,974		3	221,971
Repurchase of common shares	(11,042)			(11,042)
Repurchase of common shares to settle tax obligations	(2,623)			(2,623)
Forfeiture of employee common shares	1			0	1
Dividends/distributions	(60,479)				(59,346)		(1,133)
Net income	37,551				37,020		531
Other comprehensive loss	(18,802)					(18,802)
Ending Balance at Jun. 30, 2020	1,892,186	94,016	28	3,185,458	(1,386,001)	(20,730)	19,415
Beginning Balance at Mar. 31, 2020	1,702,670	94,016	26	2,982,363	(1,374,286)	(18,924)	19,475
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of partnership interest in real estate	466						466
Redemption of noncontrolling OP units for common shares				54			(54)
Issuance of common shares and deferred compensation amortization, net	203,043		2	203,041
Dividends/distributions	(31,318)				(30,581)		(737)
Net income	19,131				18,866		265
Other comprehensive loss	(1,806)					(1,806)
Ending Balance at Jun. 30, 2020	$ 1,892,186	$ 94,016	$ 28	$ 3,185,458	$ (1,386,001)	$ (20,730)	$ 19,415