Issuance of Common Stock - (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 10, 2015	Dec. 31, 2015	Dec. 31, 2016
Issuance of common stock (in shares)	350,000	350,000
Common stock, par value (in dollars per share)		$ 1.25	$ 1.25
Issuance of common stock	$ 8,200	$ 8,151
Payments of stock issuance costs	$ 63
Investor
Common stock, par value (in dollars per share)	$ 23.50
Individual
Common stock, par value (in dollars per share)	$ 1.25