Equity and Earnings per Common Share, Common and Preferred Stock (Details) - USD ($)					12 Months Ended
	Feb. 11, 2019	Jun. 04, 2018	Aug. 17, 2017	Mar. 29, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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)		2,750,000		5,175,000
Common stock issued, price per share (in dollars per share)		$ 0.01		$ 0.01	$ 18.17	$ 18.39
Common stock issued and sold, value				$ 81,100,000	$ 69,012,000	$ 81,237,000	$ 125,000
Proceeds from issuance of stock					7,722,000	57,917,000	0
Stock issuance expense		$ 265,000		$ 229,000
Stock exercised to purchase additional shares (in shares)		338,857
Proceeds from issuance of common stock		$ 53,800,000			$ 69,012,000	$ 81,237,000	$ 125,000
Series A Preferred Stock [Member]
Class of Stock Disclosures [Abstract]
Preferred stock, par value (in dollars per share)			$ 0.01		$ 0.01	$ 0.01
Preferred stock issued (in shares)			2,400,000		2,718,206	2,400,000
Preferred stock dividend rate			8.20%		8.20%
Proceeds from issuance of stock			$ 58,100,000
Stock issuance expense			$ 193,000
Series B Preferred Stock [Member] | Subsequent Event [Member]
Class of Stock Disclosures [Abstract]
Stock issued and sold (in shares)	1,800,000
Preferred stock, par value (in dollars per share)	$ 0.01
Stock issuance expense	$ 285,000
Percentage of offering of fixed-to-floating rate cumulative redeemable stock	8.25%