Allowance for Doubtful Accounts Receivable and Sales Returns (Activity in Allowance for Doubtful Accounts Receivable and Sales Returns) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 1,642	$ 1,535
Ending Balance	923	1,642	$ 1,535
Allowance for Doubtful Accounts Receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	1,288	966	1,010
Addition (reduction) to allowance	(355)	433	(2)
Amounts written off	(77)	0	(83)
Effects of foreign currency translation	(91)	(111)	41
Ending Balance	765	1,288	966
Allowance for Sales Returns
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	354	569	653
Addition (reduction) to allowance	(186)	(209)	(64)
Amounts written off	(9)	(6)	(21)
Effects of foreign currency translation	(1)	0	1
Ending Balance	$ 158	$ 354	$ 569