Income Taxes - Summary (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Provision for income taxes
Provision for income taxes	$ 0	$ 0
Net deferred tax assets, before valuation allowance	395,600,000	352,100,000
Unrecognized tax benefits	2,099,000	2,099,000	$ 2,099,000
Research Tax Credit Carryforward
Provision for income taxes
Tax credit carryforward	21,000,000
Federal
Provision for income taxes
Net operating loss carryforwards	1,027,500,000	950,800,000
Operating loss carryforwards, subject to expiration	347,400,000
State
Provision for income taxes
Net operating loss carryforwards	$ 696,100,000	$ 698,400,000