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Summary of Significant Accounting Policies - Reconciliation of Basic and Diluted Earnings (Losses) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings (losses) per share:
Net earnings (losses)	$ 2,035	$ 3,620	$ 1,138	$ (3,033)	$ (282)	$ (860)	$ 6,793	$ (4,175)
Weighted average number of shares outstanding – Basic (in shares)	4,218			4,218			4,218	4,218
Basic earnings (losses) per share (in dollars per share)	$ 0.48			$ (0.72)			$ 1.61	$ (0.99)
Diluted earnings (losses) per share:
Total (in shares)	4,219			4,218			4,218	4,218
Diluted earnings (losses) per share (in dollars per share)	$ 0.48			$ (0.72)			$ 1.61	$ (0.99)
Restricted Stock Units Awards
Diluted earnings (losses) per share:
Unit awards	1			0			0	0
Performance Unit Awards
Diluted earnings (losses) per share:
Unit awards	0			0			0	0