CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common shares	Additional Paid-in Capital	Cumulative Net Income	Cumulative Other Comprehensive Income	Cumulative Common Distributions	Total Equity Attributable to Common Shareholders	Total Attributable to Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2018		65,074,791
Beginning balance at Dec. 31, 2018	$ 1,028,273	$ 651	$ 998,447	$ 89,657	$ 0	$ (60,482)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	16,786			16,786
Equity in unrealized gains of an investee	66				66
Share grants	73		73
Distributions to common shareholders	(21,474)					(21,474)
Ending balance (in shares) at Mar. 31, 2019		65,074,791
Ending balance at Mar. 31, 2019	1,023,724	$ 651	998,520	106,443	66	(81,956)
Beginning balance (in shares) at Dec. 31, 2018		65,074,791
Beginning balance at Dec. 31, 2018	1,028,273	$ 651	998,447	89,657	0	(60,482)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	29,902
Equity in unrealized gains of an investee	137
Ending balance (in shares) at Jun. 30, 2019		65,088,189
Ending balance at Jun. 30, 2019	1,015,752	$ 651	998,836	119,559	137	(103,431)
Beginning balance (in shares) at Mar. 31, 2019		65,074,791
Beginning balance at Mar. 31, 2019	1,023,724	$ 651	998,520	106,443	66	(81,956)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	13,116			13,116
Equity in unrealized gains of an investee	71				71
Share grants (in shares)		15,000
Share grants	345		345
Share repurchases (in shares)		(1,362)
Share repurchases	(28)		(28)
Share forfeitures (in shares)		240
Share forfeitures	(1)		(1)
Distributions to common shareholders	(21,475)					(21,475)
Ending balance (in shares) at Jun. 30, 2019		65,088,189
Ending balance at Jun. 30, 2019	1,015,752	$ 651	998,836	119,559	$ 137	(103,431)
Beginning balance (in shares) at Dec. 31, 2019		65,180,628
Beginning balance at Dec. 31, 2019	995,690	$ 652	999,302	142,155		(146,419)	$ 995,690	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	12,694			12,846			12,846	(152)
Share grants (in shares)		6,000
Share grants	326		326				326
Share repurchases (in shares)		(951)
Share repurchases	(18)		(18)				(18)
Distributions to common shareholders	(21,510)					(21,510)	(21,510)
Contributions from noncontrolling interest	107,640		6,972				6,972	100,668
Ending balance (in shares) at Mar. 31, 2020		65,185,677
Ending balance at Mar. 31, 2020	1,094,822	$ 652	1,006,582	155,001		(167,929)	994,306	100,516
Beginning balance (in shares) at Dec. 31, 2019		65,180,628
Beginning balance at Dec. 31, 2019	995,690	$ 652	999,302	142,155		(146,419)	995,690	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	27,251
Equity in unrealized gains of an investee	0
Ending balance (in shares) at Jun. 30, 2020		65,209,564
Ending balance at Jun. 30, 2020	1,086,611	$ 652	1,007,223	169,822		(189,440)	988,257	98,354
Beginning balance (in shares) at Mar. 31, 2020		65,185,677
Beginning balance at Mar. 31, 2020	1,094,822	$ 652	1,006,582	155,001		(167,929)	994,306	100,516
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	14,557			14,821			14,821	(264)
Equity in unrealized gains of an investee	0
Share grants (in shares)		24,500
Share grants	654		654				654
Share repurchases (in shares)		(613)
Share repurchases	(13)		(13)				(13)
Distributions to common shareholders	(21,511)					(21,511)	(21,511)
Distributions to noncontrolling interest	(1,898)							(1,898)
Ending balance (in shares) at Jun. 30, 2020		65,209,564
Ending balance at Jun. 30, 2020	$ 1,086,611	$ 652	$ 1,007,223	$ 169,822		$ (189,440)	$ 988,257	$ 98,354