Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Income tax expense	$ 0	$ 0
Net operating loss carryforwards	31,500,000
Increase in valuation allowance due to deferred tax assets	38,400,000	47,200,000
Uncertain tax positions	0
Income tax expense, interest or penalties	0	$ 0
Research and Development
Income Tax Disclosure [Line Items]
Tax credit carryforwards	43,200,000
Orphan Drug
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 33,900,000
Tax credit carryforwards expiration year	2041
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 367,200,000
Net operating loss carryforwards indefinitely	$ 335,700,000
Net operating loss carryforwards expiration year	2037
Federal | Research and Development
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 43,200,000
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	369,000,000.0
State | Research and Development
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 10,800,000