CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid In Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Cumulative Common Distributions
Increase (Decrease) in Shareholders' Equity
Adjusted balance	$ 1,330,755	$ 248	$ 1,968,960	$ 169,137	$ 146	$ (807,736)
Balance beginning at Dec. 31, 2017	1,330,043	$ 248	1,968,960	108,144	60,427	(807,736)
Balance (in shares) at Dec. 31, 2017		24,786,479
Increase (Decrease) in Shareholders' Equity
Net current period other comprehensive loss	(41)				(41)
Shares forfeitures or repurchases	(11)		(11)
Shares forfeitures or repurchases (in shares)		(153)
Net income (loss) available for common shareholders	6,287			6,287
Distributions to common shareholders	(42,632)					(42,632)
Balance ending at Mar. 31, 2018	1,294,358	$ 248	1,968,949	175,424	105	(850,368)
Balance (in shares) at Mar. 31, 2018		24,786,326
Balance beginning at Dec. 31, 2018	1,778,968	$ 481	2,609,801	146,882	106	(978,302)
Balance (in shares) at Dec. 31, 2018		48,082,903
Increase (Decrease) in Shareholders' Equity
Share grants	865		865
Amounts reclassified from cumulative other comprehensive income to net income	(371)
Net current period other comprehensive loss	(32)				(32)
Share grants (in shares)		9,000
Net income (loss) available for common shareholders	34,019			34,019
Distributions to common shareholders	(26,445)					(26,445)
Balance ending at Mar. 31, 2019	$ 1,787,004	$ 481	$ 2,610,666	$ 180,901	$ (297)	$ (1,004,747)
Balance (in shares) at Mar. 31, 2019		48,091,903