Revenue Recognition and Reserve for Sales Returns and Allowances - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Reserve for sales returns and allowances	$ 15,343	$ 17,622
Minimum
Significant Accounting Policies [Line Items]
Discount on invoiced amount of products	2.00%
Maximum
Significant Accounting Policies [Line Items]
Discount on invoiced amount of products	10.00%