Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes Disclosure [Line Items]
Federal statutory income tax rate, percent	21.00%	21.00%	21.00%
Income tax expense (benefit)	$ (2,815,000)	$ 19,000	$ (589,000)
Increase in valuation allowance	37,900	8,100
Net operating loss carryforwards	$ 51,796,000	12,510,000	5,233,000
Ownership change plan description	In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period
Unrecognized tax benefits	$ 797,000	$ 797,000	$ 797,000	$ 866,000
Intellectual Property
Income Taxes Disclosure [Line Items]
Unrecognized tax benefits	800,000
Maximum | California Research And Development
Income Taxes Disclosure [Line Items]
Tax credit carryforward, amount	100,000
Domestic Tax Authority
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 211,400
Operating loss carryforwards, expiration date	Dec. 31, 2037
Net operating loss carryforwards	$ 7,600,000
Operating Loss Carryforwards Indefinitely	203,800,000
State
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 82,200
Operating loss carryforwards, expiration date	Dec. 31, 2035
Foreign Tax Authority
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 16,700
C O V I D19
Income Taxes Disclosure [Line Items]
Operating loss carryback duration under CARES Act	5 years
Percentage of net operating loss carryforwards	80.00%
Income tax expense (benefit)	$ (2,800,000)