Income Taxes - Schedule of Reconciliation of Income Taxes at Statutory Federal Income Tax Rate to Net Income Taxes (Detail) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
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| Income Tax Disclosure [Abstract] | ||
| U.S. federal taxes (benefit) at statutory rate | $ (6,361,000) | $ (7,867,000) |
| State federal income tax benefit | (69,000) | (21,000) |
| Permanent differences | (24,000) | 87,000 |
| Research and development credits | (608,000) | (237,000) |
| Change in valuation allowance due to operations | 2,758,000 | 4,766,000 |
| Acquisition-related permanent differences | 0 | 2,281,000 |
| Expiring state carryovers and other | 4,304,000 | 991,000 |
| Change in valuation allowance due to Tax Act | 0 | (6,863,000) |
| U.S. Statutory Rate Change due to Tax Act | 0 | 6,863,000 |
| Total | $ 0 | $ 0 |
| X | ||||||||||
- Definition 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 acquisition related permanent differences. No definition available.
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| X | ||||||||||
- Definition Income tax reconciliation expiring state carryovers and other. No definition available.
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| X | ||||||||||
- Definition 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 permanent differences. No definition available.
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| X | ||||||||||
- Definition Valuation allowance recorded to offset income tax expense from revaluation of deferred tax assets and liabilities due to corporate tax rate change. No definition available.
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- References No definition available.
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| X | ||||||||||
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition 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 income tax rates. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition 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 state and local income tax expense (benefit). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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