Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 135,536	$ 125,016
Research and development credit carryforwards	28,291	26,705
Capitalized research and development	12,832	15,293
Compensation related items	9,843	8,310
Operating leases	4,374
Other	4,547	4,013
Total deferred tax assets	195,423	179,337
Valuation allowance	(192,304)	(179,245)
Net deferred tax assets	3,119	92
Deferred tax liabilities:
Right-of-use assets	3,017
Amortization of goodwill	143	127
Total deferred tax liabilities	$ 3,160	$ 127