CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Shares [Member]	Common Stock [Member]	Additional Paid-in-Capital [Member]	Accumulated Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive Income [Member]	Non-controlling Interests [Member]
Beginning Balance at Dec. 31, 2017	$ 1,340,835	$ 94,016	$ 24	$ 2,818,520	$ (1,589,724)	$ 1,065	$ 16,934
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares and deferred compensation amortization, net	1,660			1,660
Repurchase of common shares	(6,336)			(6,336)
Repurchase of common shares to settle tax obligations	(2,544)			(2,544)
Forfeiture of employee common shares	(78)			(87)	9
Dividends/distributions	(44,576)				(43,774)		(802)
Net income (loss)	(14,823)				(14,315)		(508)
Other comprehensive loss	246					246
Ending Balance at Mar. 31, 2018	1,274,384	94,016	24	2,811,213	(1,647,804)	1,311	15,624
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	0			156			(156)
Issuance of common shares and deferred compensation amortization, net	1,710			1,710
Repurchase of common shares	(958)			(958)
Repurchase of common shares to settle tax obligations	(3,942)			(3,941)
Repurchase of common shares to settle tax obligations (in shares)			(1)
Forfeiture of employee common shares	(5)				(5)
Dividends/distributions	(26,363)				(25,471)		(892)
Net income (loss)	28,280				28,027		253
Other comprehensive loss	(76)					(76)
Ending Balance at Mar. 31, 2019	$ 1,345,334	$ 94,016	$ 23	$ 2,769,822	$ (1,534,539)	$ 0	$ 16,012