Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Series A Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In-Capital [Member]	Dividends in Excess of Earnings [Member]	Total
Balances at beginning of period at Dec. 31, 2018	$ 14,009	$ 10	$ 260,540	$ (10,267)	$ 264,292
Balances at beginning of period (in shares) at Dec. 31, 2018		9,775,800
Net income				13,573	13,573
Equity component of exchangeable senior notes			5,569		5,569
Net proceeds from sale of common stock		$ 1	185,623		185,624
Net proceeds from sale of common stock (in shares)		1,558,000
Net issuance of unvested restricted stock			(939)		(939)
Net issuance of unvested restricted stock (in shares)		34,028
Preferred stock dividend				(1,014)	(1,014)
Common stock dividend				(19,163)	(19,163)
Stock-based compensation			1,841		1,841
Balances at end of period at Sep. 30, 2019	14,009	$ 11	452,634	(16,871)	449,783
Balances at end of period (in shares) at Sep. 30, 2019		11,367,828
Balances at beginning of period at Jun. 30, 2019	14,009	$ 10	266,356	(14,187)	266,188
Balances at beginning of period (in shares) at Jun. 30, 2019		9,809,171
Net income				6,520	6,520
Net proceeds from sale of common stock		$ 1	185,623		185,624
Net proceeds from sale of common stock (in shares)		1,558,000
Net issuance of unvested restricted stock (in shares)		657
Preferred stock dividend				(338)	(338)
Common stock dividend				(8,866)	(8,866)
Stock-based compensation			655		655
Balances at end of period at Sep. 30, 2019	14,009	$ 11	452,634	(16,871)	449,783
Balances at end of period (in shares) at Sep. 30, 2019		11,367,828
Balances at beginning of period at Dec. 31, 2019	14,009	$ 13	553,932	(19,944)	548,010
Balances at beginning of period (in shares) at Dec. 31, 2019		12,637,043
Net income				44,397	44,397
Net proceeds from sale of common stock		$ 9	741,097		741,106
Net proceeds from sale of common stock (in shares)		9,548,866
Issuance of exchangeable senior notes			1		1
Issuance of exchangeable senior notes (in shares)		14
Net issuance of unvested restricted stock			(2,166)		(2,166)
Net issuance of unvested restricted stock (in shares)		(11,495)
Preferred stock dividend				(1,014)	(1,014)
Common stock dividend				(62,826)	(62,826)
Stock-based compensation			2,488		2,488
Balances at end of period at Sep. 30, 2020	14,009	$ 22	1,295,352	(39,387)	1,269,996
Balances at end of period (in shares) at Sep. 30, 2020		22,174,428
Balances at beginning of period at Jun. 30, 2020	14,009	$ 19	988,220	(32,277)	969,971
Balances at beginning of period (in shares) at Jun. 30, 2020		18,614,561
Net income				19,215	19,215
Net proceeds from sale of common stock		$ 3	306,291		306,294
Net proceeds from sale of common stock (in shares)		3,559,867
Preferred stock dividend				(338)	(338)
Common stock dividend				(25,987)	(25,987)
Stock-based compensation			841		841
Balances at end of period at Sep. 30, 2020	$ 14,009	$ 22	$ 1,295,352	$ (39,387)	$ 1,269,996
Balances at end of period (in shares) at Sep. 30, 2020		22,174,428