Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Provision for income taxes	$ 0	$ 0	$ 0
Deferred tax assets, net operating loss carryforwards	13,418,000	23,947,000
Research and development credit carryforwards	3,813,000	2,995,000
Unrecognized tax benefits	901,000	$ 746,000	$ 399,000
Federal Income Tax
Income Tax Disclosure [Line Items]
Deferred tax assets, net operating loss carryforwards	35,800,000
Deferred tax assets, operating loss carryforwards subject to expire	$ 11,700,000
Tax credit carry forward expiration year	2037
Deferred tax assets, operating loss carryforwards subject to do not expire	$ 24,100,000
Research and development credit carryforwards	2,600,000
California State Income Tax
Income Tax Disclosure [Line Items]
Deferred tax assets, net operating loss carryforwards	83,800,000
Deferred tax assets, operating loss carryforwards subject to expire	$ 83,800,000
Tax credit carry forward expiration year	2036
Research and development credit carryforwards	$ 2,500,000