Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provision for income taxes	$ 1,912,000	$ 2,951,000	$ 1,606,000
Effective income tax rate	(3.60%)	(7.50%)	(2.00%)
Effective income tax rate, exclusive of discrete items	(3.10%)	(9.60%)	(2.80%)
Discrete tax benefit (expenses)	$ 200,000
Net deferred tax liabilities	14,000	$ 993,000
Recognized UTP	100,000	600,000	$ 100,000
De-recognized UTP		400,000
Interest expense relating to UTPs	40,000	100,000
Valuation allowance	92,778,000	$ 84,097,000
Valuation allowance increase	8,700,000
U.S. Federal net operating loss carryforwards	164,100,000
State Of California
Income Taxes [Line Items]
State operating loss carryforwards	209,300,000
Foreign Tax Authority
Income Taxes [Line Items]
Foreign tax credit carryforwards	100,000
Internal Revenue Service (IRS) | Research Tax Credit Carryforward
Income Taxes [Line Items]
Research and development tax credit carryforwards	500,000
State and Local Jurisdiction | Research Tax Credit Carryforward
Income Taxes [Line Items]
Research and development tax credit carryforwards	$ 100,000