Condensed Consolidated Statement of Changes in Equity - USD ($) $ in Thousands		Total	Total Stockholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings/(Accumulated Deficit)	Non-controlling Interest
Beginning balance (in shares) at Dec. 31, 2017		31,335,938
Beginning balance at Dec. 31, 2017		$ 620,961	$ 600,099				$ 20,862
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Shares Issued As Payment of Incentive Fee		29	29
Contributions from non-controlling interests		11,900					11,900
Dividends		(38,152)	(37,891)				(261)
Distributions to non-controlling interests		(11,744)					(11,744)
Adjustment to non-controlling interests		$ 0	(33)				33
Director OP LTIP Units exercised		3,334
Repurchase of shares of common stock (in shares)		(1,186,058)
Repurchase of shares of common stock		$ (17,593)	(17,593)
Share-based long term incentive plan unit redemption and distribution		$ 296	294				2
Ending balance (in shares) at Sep. 30, 2018		30,155,055
Ending balance at Sep. 30, 2018		$ 616,678	593,797				22,881
Change In Shareholders' Equity Resulting From Operations [Abstract]
Net investment income		32,911
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		21,810
Change in net unrealized gain (loss) on investments, other secured borrowings, financial derivatives, and foreign currency translation		(3,740)
Net increase in equity resulting from operations		50,981	48,892				2,089
Net increase (decrease) in equity from transactions		(55,264)	(55,194)				(70)
Net increase (decrease) in equity		$ (4,283)	(6,302)				2,019
Beginning balance (in shares) at Jun. 30, 2018		30,149,880
Beginning balance at Jun. 30, 2018		$ 613,275	599,567				13,708
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Shares Issued As Payment of Incentive Fee		29	29
Contributions from non-controlling interests		9,735					9,735
Dividends		(12,651)	(12,564)				(87)
Distributions to non-controlling interests		(1,287)					(1,287)
Adjustment to non-controlling interests		$ 0	2				(2)
Director OP LTIP Units exercised		3,334
Repurchase of shares of common stock (in shares)		0
Repurchase of shares of common stock		$ 0	0
Share-based long term incentive plan unit redemption and distribution		$ 103	102				1
Ending balance (in shares) at Sep. 30, 2018		30,155,055
Ending balance at Sep. 30, 2018		$ 616,678	593,797				22,881
Change In Shareholders' Equity Resulting From Operations [Abstract]
Net investment income		11,678
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		10,102
Change in net unrealized gain (loss) on investments, other secured borrowings, financial derivatives, and foreign currency translation		(14,306)
Net increase in equity resulting from operations		7,474	6,661				813
Net increase (decrease) in equity from transactions		(4,071)	(12,431)				8,360
Net increase (decrease) in equity		$ 3,403	(5,770)				9,173
Beginning balance (in shares) at Dec. 31, 2018		29,796,601		29,796,601
Beginning balance at Dec. 31, 2018		$ 595,170	563,833		$ 665,356	$ (101,523)	31,337
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Share conversion	[1]			$ 30	(30)
Net income (loss)		16,488	15,408			15,408	1,080
Contributions from non-controlling interests		2,512					2,512
Dividends	[2]	(16,764)	(16,360)			(16,360)	(404)
Distributions to non-controlling interests		(4,306)					(4,306)
Adjustment to non-controlling interests			(4)		(4)		4
Repurchase of shares of common stock (in shares)				(50,825)
Repurchase of shares of common stock		(782)	(782)		(782)
Share-based long term incentive plan unit awards		116	114		114		2
Ending balance (in shares) at Mar. 31, 2019				29,745,776
Ending balance at Mar. 31, 2019		$ 592,434	562,209	$ 30	664,654	(102,475)	30,225
Beginning balance (in shares) at Dec. 31, 2018		29,796,601		29,796,601
Beginning balance at Dec. 31, 2018		$ 595,170	563,833		665,356	(101,523)	31,337
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Dividends		$ (44,059)
Director OP LTIP Units exercised		3,610
Repurchase of shares of common stock (in shares)		(50,825)
Repurchase of shares of common stock		$ (800)
Ending balance (in shares) at Sep. 30, 2019		33,774,386		33,774,386
Ending balance at Sep. 30, 2019		$ 668,967	635,446	$ 34	734,628	(99,216)	33,521
Change In Shareholders' Equity Resulting From Operations [Abstract]
Stock Issued During Period, Shares, New Issues		4,025,000
Beginning balance (in shares) at Mar. 31, 2019				29,745,776
Beginning balance at Mar. 31, 2019		$ 592,434	562,209	$ 30	664,654	(102,475)	30,225
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net income (loss)		13,656	12,644			12,644	1,012
Contributions from non-controlling interests		4,936					4,936
Dividends	[2]	(12,801)	(12,493)			(12,493)	(308)
Distributions to non-controlling interests		(5,225)					(5,225)
Share-based long term incentive plan unit awards		$ 114	110		110		4
Ending balance (in shares) at Jun. 30, 2019		29,745,776		29,745,776
Ending balance at Jun. 30, 2019		$ 593,114	562,470	$ 30	664,764	(102,324)	30,644
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net income (loss)		18,712	17,293			17,293	1,419
Contributions from non-controlling interests		9,428					9,428
Dividends	[2]	(14,494)	(14,185)			(14,185)	(309)
Distributions to non-controlling interests		$ (7,719)					(7,719)
Adjustment to non-controlling interests			(56)		(56)		56
Director OP LTIP Units exercised		3,610
Repurchase of shares of common stock (in shares)		0
Share-based long term incentive plan unit awards		$ 116	114		114		2
Ending balance (in shares) at Sep. 30, 2019		33,774,386		33,774,386
Ending balance at Sep. 30, 2019		$ 668,967	635,446	$ 34	734,628	(99,216)	33,521
Change In Shareholders' Equity Resulting From Operations [Abstract]
Stock Issued During Period, Shares, New Issues	[3]	4,025,000
Stock Issued During Period, Value, New Issues	[3]	$ 69,810	$ 69,810	$ 4	$ 69,806	$ 0	$ 0

[1] See Note 1 for further details on the share conversion.

[2] For the three- and nine-month periods ended September 30, 2019, dividends totaling $0.42 and $1.39 per share of common stock outstanding were declared.

[3] Net of underwriters' discount and offering costs.