Equity and Earnings per Common Share, Common and Preferred Stock (Details) - USD ($)			3 Months Ended				6 Months Ended
	Apr. 28, 2020	Jun. 04, 2018	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Class of Stock Disclosures [Abstract]
Date of conducting IPO and concurrent private placement of common stock							Oct. 09, 2013
Stock issued and sold (in shares)	527,010	2,750,000
Common stock issued, price per share (in dollars per share)		$ 0.01
Stock exercised to purchase additional shares (in shares)		338,857
Proceeds from issuance of common stock		$ 53,800,000					$ 252,000	$ 3,481,000
Stock issuance expense		$ 265,000
Earnings Per Share, Other Disclosures [Abstract]
Issuance of common stock (in shares)	527,010	2,750,000
Common dividends declared (in dollars per share)	$ 0.40		$ 0.27	$ 0.27	$ 0.27	$ 0.40
Series A Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Preferred stock dividend rate							8.20%
Preferred stock, par value (in dollars per share)			0.01				$ 0.01		$ 0.01
Cash redemption price (in dollars per share)			$ 25.00				$ 25.00
Shares issued upon conversion, preferred stock (in shares)			2.62881				2.62881
Percentage of cash dividends rate							8.20%
Liquidation preference per share (in dollars per share)			$ 25.00				$ 25.00
Cumulative cash dividends (in dollars per share)							2.05
Series B Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Preferred stock, par value (in dollars per share)			0.01				0.01		$ 0.01
Cash redemption price (in dollars per share)			$ 25.00				$ 25.00
Shares issued upon conversion, preferred stock (in shares)			2.68962				2.68962
Percentage of offering of fixed-to-floating rate cumulative redeemable stock			8.25%				8.25%
Series B Preferred Stock [Member] | LIBOR [Member]
Class of Stock Disclosures [Abstract]
Shares issued upon conversion, preferred stock (in shares)			2.0625				2.0625
Liquidation preference per share (in dollars per share)			$ 25.00				$ 25.00
Percentage of offering of fixed-to-floating rate cumulative redeemable stock			8.25%				8.25%
Term of floating rate							3 months
Basis spread on variable rate							5.631%