Commitments and Contingencies (Schedule of Warranty Activity) (Details) - Accrued Expenses - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 1,210	$ 474	$ 460
Additions	1,936	1,399	667
Charges	(1,063)	(663)	(653)
Ending balance	$ 2,083	$ 1,210	$ 474