Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Reserves and accruals	$ 25,527	$ 16,413
Net operating loss carryovers	33,321	27,023
Research and development credit carryovers	28,759	27,595
Deferred stock-based compensation	4,292	5,834
Depreciation and amortization	554
Other tax credits	2,738	2,738
Gross deferred tax assets	95,191	79,603
Valuation allowance	(74,480)	(64,545)	$ (75,199)	$ (38,644)
Gross deferred tax assets after valuation allowance	20,711	15,058
Deferred tax liabilities:
Depreciation and amortization	0	(1,189)
Intangibles	(1,417)	(899)
Convertible notes	(8,603)	(10,233)
Other	(510)	(510)
Gross deferred tax liabilities	(10,530)	(12,831)
Net deferred tax assets	$ 10,181	$ 2,227