Warranty Accrual Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 2,638	$ 3,148
Charged to cost of revenues	3,440	1,308
Actual warranty expenditures	(2,681)	(1,745)
Balance at end of period	$ 3,397	$ 2,711