Income Taxes - Reconciliation of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	(5.40%)	(5.90%)	(5.80%)
Foreign rate differential	0.00%	0.00%	(0.10%)
Research and development tax credits	(0.90%)	(1.10%)	(1.10%)
Change in fair value of preferred stock warrant liability	0.00%	0.00%	0.10%
Other permanent differences	3.70%	0.90%	1.40%
Change in deferred tax asset valuation allowance	23.70%	27.20%	26.80%
Other	(0.10%)	0.10%	(0.30%)
Effective income tax rate	0.00%	0.20%	0.00%