Other Accrued Liabilities, Accrued Warranty Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Product Warranty Accrual [Roll Forward]
Accrual at beginning of period	$ 238	$ 178
Additions charged to warranty expense	68	63
Expiring warranties/claimed satisfied	(34)	(46)
Total	$ 238	$ 178	$ 272	$ 238	$ 195
Less: current portion			(183)	$ (156)	(120)
Total long-term accrued warranty costs			$ 89		$ 75
Minimum [Member]
Accrued warranty costs [Abstract]
Standard warranty period	1 year
Offered warranty period	3 years
Maximum [Member]
Accrued warranty costs [Abstract]
Standard warranty period	2 years
Offered warranty period	4 years