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Income Taxes - Reconciliation of Total Income Tax Provision (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the total income tax provision tax rate [Abstract]
Income tax expense (benefit) at federal statutory rate	(21.00%)	(21.00%)
Income tax expense (benefit) at state statutory rate	(12.20%)	(6.10%)
Change in valuation allowance	23.00%	34.80%
Change in state rate	(1.30%)	(0.10%)
Permanent interest adjustments	1.10%	0.70%
Stock compensation	13.70%	1.80%
Research credit	(1.80%)	(1.40%)
Return to provision	3.10%	(3.40%)
NOLs expiring and adjustments to NOL	19.20%
Mark to market adjustment	(24.00%)	(5.30%)
Other, net	0.20%
Total income tax provision	0.00%	0.00%

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Effective income tax rate reconciliation mark to market adjustment.

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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 net operating loss expiration.

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Effective income tax rate reconciliation tax return to provision.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable permanent interest adjustments.

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

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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 difference between reported income tax expense (benefit) and 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 share-based payment arrangement.

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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 research tax credit.

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