Equity and Earnings per Common Share, Common and Preferred Stock (Details) - USD ($)			3 Months Ended				6 Months Ended
	Feb. 11, 2019	Jun. 04, 2018	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Class of Stock Disclosures [Abstract]
Date of conducting IPO and concurrent private placement of common stock			Oct. 09, 2013
Common stock issued, price per share (in dollars per share)		$ 0.01	$ 16.42		$ 18.17		$ 16.42	$ 18.17
Stock issued and sold (in shares)		2,750,000
Preferred stock, par value (in dollars per share)			$ 0.01				$ 0.01
Proceeds from issuance of stock							$ 49,642,000	$ 3,981,000
Stock issuance expense		$ 265,000
Stock exercised to purchase additional shares (in shares)		338,857
Proceeds from issuance of common stock		$ 53,800,000					$ 4,020,000	$ 53,619,000
Series A Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Preferred stock dividend rate			8.20%				8.20%
Preferred stock, par value (in dollars per share)			$ 0.01				$ 0.01		$ 0.01
Preferred stock issued (in shares)			2,781,635				2,781,635		2,718,206
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%				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		$ 0.01
Preferred stock issued (in shares)	1,800,000		2,000,000				2,000,000		0
Proceeds from issuance of stock	$ 48,400,000
Stock issuance expense	$ 285,000
Stock exercised to purchase additional shares (in shares)	200,000
Percentage of offering of fixed-to-floating rate cumulative redeemable stock	8.30%
Cash redemption price (in dollars per share)	$ 25.00
Shares issued upon conversion, preferred stock (in shares)	2.68962
Series B Preferred Stock [Member] | LIBOR [Member]
Class of Stock Disclosures [Abstract]
Percentage of offering of fixed-to-floating rate cumulative redeemable stock			8.25%				8.25%
Shares issued upon conversion, preferred stock (in shares)			2.0625				2.0625
Liquidation preference per share (in dollars per share)			$ 25.00				$ 25.00
Term of floating rate							3 months
Basis spread on variable rate							5.631%
Common Stock [Member]
Class of Stock Disclosures [Abstract]
Stock issued and sold (in shares)			238,435	6,000	3,097,113	0