Schedule II - Valuation and Qualifying Accounts and Reserves (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation Allowance for Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of the period	$ 109,030	$ 84,960	$ 72,061
Charged to income	(37,515)	24,070	12,899
Balance at end of the period	71,515	109,030	84,960
Allowance for Rebates [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of the period	3,842	4,470	939
Charged to income	17,236	(1,204)	2,118
Charged to other accounts	(132)	11,501	6,360
Deductions	(15,298)	(10,925)	(4,947)
Balance at end of the period	5,648	3,842	4,470
Allowance for Price Adjustments and Chargebacks [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of the period	602	383	400
Charged to income	6,738	36	(2,118)
Charged to other accounts	(3)	1,711	3,259
Deductions	(3,412)	(1,528)	(1,158)
Balance at end of the period	3,925	$ 602	383
Allowance for inventory obsolescence [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Charged to income	243		213
Charged to other accounts			$ (213)
Balance at end of the period	$ 243