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		Preferred Stock [Member]	Preferred Stock [Member] Total Stockholders' Equity	Preferred Stock [Member] Preferred Stock [Member]	Common Stock		Common Stock Total Stockholders' Equity	Common Stock Common Stock	Common Stock Additional Paid-in Capital
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
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		49,911		46,676					3,235
Shares Issued As Payment of Incentive Fee		71		71
Contributions from non-controlling interests		21,532							21,532
Distributions to non-controlling interests		(23,853)							(23,853)
Adjustment to non-controlling interests		$ 0		(369)					369
Stock issued during period, shares, conversion of units		(3,334)
Repurchase of shares of common stock (in shares)		(1,547,148)
Repurchase of shares of common stock		$ (23,131)		(23,131)
Share-based long term incentive plan unit awards		$ 415		412					3
Ending balance (in shares) at Dec. 31, 2018		29,796,601				29,796,601
Ending balance at Dec. 31, 2018		$ 595,170		563,833		$ 0	$ 665,356	$ (101,523)	31,337
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Dividends declared (in usd per share)		$ 1.64
Net investment income		$ 43,125
Total net realized gain (loss)		31,388
Net Unrealized Gain (Loss)		(24,602)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		49,911		46,676					3,235
Dividends		(50,736)	[1]	(50,388)	[1]				(348)	[1]				$ (49,576)
Share-based long term incentive plan unit redemption and distribution		0		(9,537)					9,537
Net increase (decrease) in equity from transactions		(75,702)		(82,942)					7,240
Stockholders' Equity, Period Increase (Decrease)		(25,791)		(36,266)					10,475
Preferred Stock, Value, Outstanding		0
Share conversion	[2]					$ 30	(30)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 63,177		57,933				57,933	5,244
Stock Issued During Period, Shares, New Issues		8,855,000												8,855,000	[3]
Stock Issued During Period, Value, New Issues	[3]										$ 111,034	$ 111,034	$ 111,034	$ 156,328		$ 156,328	$ 9	$ 156,319
Shares Issued As Payment of Incentive Fee, Shares		0
Contributions from non-controlling interests		$ 27,650							27,650
Dividends	[4]	(59,824)		(58,499)				(58,499)	(1,325)
Dividends, Preferred Stock, Cash	[5]	(1,466)		(1,466)				(1,466)
Distributions to non-controlling interests		$ (23,063)							(23,063)
Adjustment to non-controlling interests				(392)			(392)		392
Stock issued during period, shares, conversion of units						47,167
Stock Issued During Period, Value, Conversion of Units				812			812		812
Repurchase of shares of common stock (in shares)		(50,825)				(50,825)
Repurchase of shares of common stock		$ (782)		(782)			(782)
Share-based long term incentive plan unit awards		$ 475		464			464		11
Ending balance (in shares) at Dec. 31, 2019		38,647,943				38,647,943
Ending balance at Dec. 31, 2019		$ 868,699		829,265		$ 39	821,747	(103,555)	39,434
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Dividends declared (in usd per share)		$ 1.81
Preferred Stock, Dividends Per Share, Declared		$ 0.45938
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 63,177		57,933				57,933	5,244
Dividends		(59,824)												$ (58,499)
Preferred Stock, Value, Outstanding		111,034
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 28,377		25,008				25,008	3,369
Stock Issued During Period, Shares, New Issues		5,290,000												5,290,000	[3]
Stock Issued During Period, Value, New Issues	[3]													$ 95,292		95,292	5	95,287
Shares Issued As Payment of Incentive Fee, Shares		637												637
Shares Issued As Payment of Incentive Fee														$ 12		$ 12	$ 0	$ 12
Contributions from non-controlling interests		$ 8,270							8,270
Dividends	[4]	(56,023)		(55,211)				(55,211)	(812)
Dividends, Preferred Stock, Cash	[5]	(7,763)		(7,763)				(7,763)	0
Distributions to non-controlling interests		$ (12,958)							(12,958)
Adjustment to non-controlling interests				(1,480)			(1,480)		1,480
Stock issued during period, shares, conversion of units						133,154
Stock Issued During Period, Value, Conversion of Units				2,437			2,437		2,437
Repurchase of shares of common stock (in shares)		(290,050)				(290,050)
Repurchase of shares of common stock		$ (3,056)		(3,056)			(3,056)
Share-based long term incentive plan unit awards		$ 722		711			711		11
Ending balance (in shares) at Dec. 31, 2020		43,781,684				43,781,684
Ending balance at Dec. 31, 2020		$ 921,572		885,215		$ 44	$ 915,658	(141,521)	36,357
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Dividends declared (in usd per share)		$ 1.26
Preferred Stock, Dividends Per Share, Declared		$ 1.265625
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 28,377		$ 25,008				$ 25,008	$ 3,369
Dividends		(56,023)												$ (55,211)
Preferred Stock, Value, Outstanding		$ 111,034

[1] For the year ended December 31, 2018, dividends totaling $1.64 per common share and convertible unit outstanding, were declared.

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

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

[4] For the years ended December 31, 2020 and 2019, dividends totaling $1.26 and $1.81, respectively, per share of common stock and convertible unit outstanding, were declared.

[5] For the years ended December 31, 2020 and 2019, dividends totaling $1.265625 and $0.45938, respectively, per share of preferred stock was declared.