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
Balance (in shares) at Dec. 31, 2018		48,082,903
Balance beginning at Dec. 31, 2018	$ 1,778,968	$ 481	$ 2,609,801	$ 146,882	$ 106	$ (978,302)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		9,000
Share grants	865		865
Amount reclassified from cumulative other comprehensive income to net income	(371)				(371)
Net current period other comprehensive loss	(32)				(32)
Net income	34,019			34,019
Distributions to common shareholders	(26,445)					(26,445)
Balance (in shares) at Mar. 31, 2019		48,091,903
Balance ending at Mar. 31, 2019	1,787,004	$ 481	2,610,666	180,901	(297)	(1,004,747)
Balance (in shares) at Dec. 31, 2019		48,201,941
Balance beginning at Dec. 31, 2019	1,705,754	$ 482	2,612,425	177,217	(200)	(1,084,170)
Increase (Decrease) in Shareholders' Equity
Share grants	379		379
Share repurchases (in shares)		(1,012)
Share repurchases	(27)		(27)
Net current period other comprehensive loss	(61)				(61)
Net income	10,840			10,840
Distributions to common shareholders	(26,511)					(26,511)
Balance (in shares) at Mar. 31, 2020		48,200,929
Balance ending at Mar. 31, 2020	$ 1,690,374	$ 482	$ 2,612,777	$ 188,057	$ (261)	$ (1,110,681)