Inventories (Allowance) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Inventory Valuation Reserves [Roll Forward]
Balance, beginning of period	$ 1,382	$ 757
Provisions for excess and obsolete inventories	60	137
Inventories written off	0	0
Balance, end of period	$ 1,442	$ 894