Income Taxes - Reconciliation of Federal Statutory Income Tax Rate and Effective Income Tax Rate (Detail)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%
Change in valuation allowance	(4.00%)	(1.00%)
State income taxes, net of federal effect	7.00%
Warrant liability FMV adjustment		1.00%
Research and development credits	3.00%	4.00%
Removal of net operating losses and other credits	(27.00%)	(22.00%)
Impact of state tax rate change	4.00%
Stock compensation and other permanent items	(4.00%)	(3.00%)

Effective income tax rate reconciliation deductible expense share based compensation and other permanent items.

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Effective income tax rate reconciliation fair market value of warrant liability adjustment.

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- Definition

Effective income tax rate reconciliation operating loss and tax credits other.

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Effective income tax rate reconciliation tax credits research and development.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage 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 changes in the valuation allowance for deferred tax assets.

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Percentage 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 applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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-Name Accounting Standards Codification
-Topic 740
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