Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 141,176	$ 135,536
Research and development credit carryforwards	28,892	28,291
Capitalized research and development	10,756	12,832
Compensation related items	10,957	9,843
Operating leases	4,214	4,374
Other	6,051	4,547
Total deferred tax assets	202,046	195,423
Valuation allowance	(199,042)	(192,304)
Net deferred tax assets	3,004	3,119
Deferred tax liabilities:
Right-of-use assets	2,892	3,017
Amortization of goodwill	163	143
Total deferred tax liabilities	$ 3,055	$ 3,160