Income Taxes - Summary (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Provision for income taxes
Provision for income taxes	$ 0	$ 0
Net deferred tax assets, before valuation allowance	352,100,000	284,200,000
Unrecognized tax benefits	2,099,000	2,099,000	$ 2,606,000
Research Tax Credit Carryforward
Provision for income taxes
Tax credit carryforward	21,000,000
Federal
Provision for income taxes
Net operating loss carryforwards	950,800,000	894,300,000
Operating loss carryforwards, subject to expiration	347,400,000
State
Provision for income taxes
Net operating loss carryforwards	$ 698,400,000	$ 662,200,000