Difference Between Provision for Income Taxes and Amounts Computed by Applying Federal Statutory Income Tax Rate to Loss before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory tax	$ (7,838)	$ (8,891)	$ (11,352)
Federal research credits	(1,065)	(1,874)	(2,159)
State research credits	(642)	(822)	(767)
Expiration of federal carryovers	7,284	4,858	4,651
Change in valuation allowance	1,361	6,379	10,482
Compensation related items	3,257	1,794	460
State taxes	(1,710)	(1,127)	(1,294)
Revision to prior year items	(664)
Other	342	171	298
Provision for income taxes	$ 325	$ 488	$ 319

Income tax reconciliation difference in reported and expected deferred tax items.

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Income tax reconciliation, expiration of federal net operating losses.

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Income tax reconciliation state tax credits research.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under share-based payment arrangement. Includes, but is not limited to, expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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