Product Warranty (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 593	$ 616	$ 578
Cost of warranty claims	(72)	0	(17)
Accruals for product warranties	66	(23)	55
Balance at end of period	$ 587	$ 593	$ 616
Minimum
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Standard product warranty period	90 days
Maximum
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Standard product warranty period	3 years