Income Taxes - Reconciliation of U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate (Details)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Effective income tax rate reconciliation    
Federal income tax expense at statutory rate 21.00% 21.00%
State taxes—net of federal benefit 5.00% 5.00%
Change in fair value of preferred stock tranche obligations 0.00% 0.00%
Permanent differences and other (1.00%) (0.00%)
Federal & state R&D credits 2.00% 1.00%
Increase in valuation allowance (27.00%) (27.00%)
Effective income tax rate 0.00% 0.00%