Income Taxes - Components of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carry forwards	$ 57,404	$ 41,251	$ 40,505
Research credits	11,480	22,082	9,045
Stock based compensation	5,546	4,828	3,703
Deferred revenue	1,380	2,280	1,893
Development costs	7,180	5,504	5,950
Returns and allowances	2,178	1,363	4,161
Other, net	10,530	9,887	9,082
Total deferred tax assets before valuation allowance	95,698	87,195	74,339
Valuation allowance	(84,822)	(71,815)	(45,983)
Total deferred tax assets	10,876	15,380	28,356
Deferred tax liabilities:
Basis difference in debt	(447)	(713)	(907)
Depreciation and amortization differences	(17,104)	(21,446)	(34,088)
Net deferred tax liabilities	$ (6,675)	$ (6,779)	$ (6,639)