Income Taxes - Income Tax Provision (Benefit) Differs from Computed Using Federal Statutory Rate Applied to Income before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax provision computed at the federal statutory rate	$ (24,777)	$ (17,619)	$ (15,236)
State tax, net of federal benefit	(261)	232	66
Research credits	(3,232)	(2,974)	(2,134)
Change in tax credit carryforwards	11,042	(4,965)	0
Transaction costs	0	0	(11)
Officers compensation	1,159	1,577	1,895
Stock based compensation	556	535	299
Permanent items and other	12	(487)	21,742
Domestic manufacturing deduction	0	0	(630)
Tax differential on foreign earnings	15	1,435	1,570
Change in tax rate	(744)	(903)	(519)
Valuation allowance	13,917	23,575	(4,856)
Total income tax (benefit) provision	$ (2,313)	$ 406	$ 2,186