Warranty (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Warranty [Abstract]
Product warranty period	5 years
Beginning balance	$ 603	$ 600
Amounts charged (credited) to expense	116	43
Actual warranty costs paid	(75)	(57)
Ending balance	$ 644	$ 586