Stockholders' Equity of the Company - Schedule of Common Stock Issued and Proceeds Received Dividend Reinvestments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 28, 2015
Stockholders' Equity
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Dividend Reinvestment and Stock Purchase Plan (DRIP)
Stockholders' Equity
Common stock, shares authorized (in shares)				3,500,000
Issuance of common stock (in shares)	1,399	2,141	2,687
Dividend reinvestments/stock purchases under the DRSPP	$ 136	$ 223	$ 277