Inventories (Allowance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for excess and obsolete inventories:
Balance, beginning of period	$ 757	$ 714	$ 579
Provisions for excess and obsolete inventories	625	178	135
Inventories written off	0	(135)	0
Balance, end of period	$ 1,382	$ 757	$ 714