Income Taxes - Reconciliation of the Company's Effective Income Tax Rate to the Federal Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal income tax at the statutory rate	$ 435	$ 5,902	$ 5,518
State income taxes, net of federal benefit	526	(215)	339
Difference between statutory and foreign tax rates	43	7	(560)
Permanent differences	1,139	725	300
Executive compensation limitation	7,596	1,167	0
Research and development	(4,911)	(6,908)	(2,380)
Return to provision adjustment	(9)	1,780	23
Change in liability for unrecognized tax benefits	1,191	1,768	7
Excess stock-based compensation benefit	(4,999)	(8,907)	(1,819)
Change in valuation allowance	368	1,984	1,949
Tax effects of intercompany transactions	16	1,004	(277)
Adjustments to deferred tax assets, net resulting from enactment of new tax law	0	0	7,601
Other	(207)	592	(147)
Provision for income taxes	$ 1,188	$ (1,101)	$ 10,554
Effective tax rate	57.40%	(3.90%)	66.90%