Deferred Tax Assets, Valuation Allowance, Percentage

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Income Taxes [Line Items]

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Operating Loss Carryforwards, Expiration Year

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Research and Development Credits, Expiration Year

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Amount of deferred tax expense from write-off of the deferred tax asset related to deductible stock options at exercise.

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

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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 research tax credit.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Statutory federal income tax rate	21.00%	21.00%	34.00%
Benefits related to stock options	$ 2,120,000
Deferred tax asset valuation allowance percentage in each of the last two years	100.00%
Scenario, Plan
Income Taxes [Line Items]
Statutory federal income tax rate	21.00%
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating loss carryforwards	$ 136,202,000
Operating loss carryforwards, expiration year	2037
Research and development credits	$ 733,000
Research and development credits, expiration year	2034
State and Local Jurisdiction
Income Taxes [Line Items]
Net operating loss carryforwards	$ 116,218,000
Operating loss carryforwards, expiration year	2037
Research and development credits	$ 176,000
Research and development credits, expiration year	2034
State and Local Jurisdiction \| Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating loss carryforwards	$ 20,938,000