Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 0	$ 0
Valuation allowance	56,666,000	48,935,000
Net operating loss	(32,403,000)	(31,897,000)
Research and development credits	100,000
Deferred tax assets for net operating losses		600,000
Research credits	100,000
Unrecognize interest or penalties.	62,000,000	50,000,000
Unrecognized tax benefits	8,860,000	$ 8,235,000	$ 7,623,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss	103,100,000
Net operating loss carryforwards	181,600,000
Research and development credits	9,600,000
Orphan drug tax credit, carryforwards	2,200,000
California [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss	1,800,000
Net operating loss carryforwards	92,800,000
Research and development credits	4,300,000
Unrecognized tax benefits	$ 7,400