Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Reserves and accruals	$ 20,622	$ 17,090
Net operating loss carryforwards	33,811	29,900
Research and development credit carryforwards	36,914	36,446
Deferred stock-based compensation	1,675	2,201
Intangibles	8,224	2,585
Operating lease liabilities	5,877
Capitalized research and development expenses	10,897
Other	0	939
Gross deferred tax assets	118,020	89,161
Valuation allowance	(95,518)	(77,144)	$ (77,756)	$ (74,480)
Gross deferred tax assets after valuation allowance	22,502	12,017
Deferred tax liabilities:
Depreciation	(1,272)	(391)
Convertible notes	(6,275)	(2,931)
Operating lease right-of-use assets	(4,061)
Other	(319)
Gross deferred tax liabilities	(11,927)	(3,322)
Net deferred tax assets	$ 10,575	$ 8,695