Commitments and Contingencies - Accrued Warranty Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Movement in Standard Product Warranty Accrual
Warranty liability balance, beginning of the year	$ 2,553	$ 2,600
Product warranty accruals	1,116	2,025
Adjustments for payments made	(1,848)	(2,072)
Warranty liability balance, end of the year	$ 1,821	$ 2,553