Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities, Current [Abstract]
Royalties and other fulfillment costs	$ 2,965	$ 2,629
Employee compensation, commissions and benefits	4,384	5,136
Sales, VAT and other taxes payable	1,782	2,215
Other	3,234	4,402
Total accrued and other current liabilities	$ 12,365	$ 14,382