Warranty Accrual Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 2,638	$ 3,148
Charged to cost of revenues	1,993	976
Actual warranty expenditures	(1,801)	(1,138)
Balance at end of period	$ 2,830	$ 2,986