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, 2020	Dec. 31, 2019
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 516
Ending Balance	629	$ 516
Allowance for Doubtful Accounts Receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	484	475
Addition to allowance	117	24
Amounts written off	(30)	0
Effects of foreign currency translation	27	(15)
Ending Balance	598	484
Allowance for Sales Returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	32	85
Addition to allowance	(1)	(32)
Amounts written off	0	(21)
Ending Balance	$ 31	$ 32