Schedule II-Valuation And Qualifying Account And Reserve (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	$ 103
Balance at End of Period	502	$ 103
Accounts receivable allowance
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	103	120	$ 36
Additions/Charged to Expense	484	23	103
Deductions	(85)	(40)	(19)
Balance at End of Period	502	103	120
Warranty allowance
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	1,076	1,178	344
Additions/Charged to Expense	885	672	2,089
Deductions	(938)	(774)	(1,255)
Balance at End of Period	$ 1,023	$ 1,076	$ 1,178