Income Taxes - Additional Information (Details)		12 Months Ended
	Oct. 02, 2017	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Income Tax Disclosure [Line Items]
Conversion ratio	5.65
Income tax benefits		$ 0	$ 0	$ 0
Federal statutory income tax rate		21.00%	21.00%	21.00%
Research and orphan drug credit carryforwards		$ 40,077,000	$ 31,142,000
Unrecognized tax benefits		$ 0
Income tax examination, description		There are currently no pending income tax examinations. The Company's tax years that are open under statute are from December 31, 2018 to the present, although carryforward attributes that were generated prior to 2018 may still be adjusted upon examination by the IRS or state tax authorities if they either have been or will be used in a future period.
Accrued interest or penalties related to uncertain tax positions		$ 0	0
Income Tax Examination, Penalties and Interest Expense		0	$ 0
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards		870,900,000
Net operating loss carryforwards, subject to expiration		$ 16,600,000
Net operating loss carryforwards expiration year		2037
Net operating loss carryforwards, carried forward indefinitely		$ 854,300,000
Research and orphan drug credit carryforwards		$ 36,600,000
Tax credit carryforwards expiration year		2037
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards		$ 688,800,000
Net operating loss carryforwards expiration year		2035
Research and orphan drug credit carryforwards		$ 4,500,000
Tax credit carryforwards expiration year		2032
Foreign Tax Authority
Income Tax Disclosure [Line Items]
Net operating loss carryforwards		$ 19,300,000
Tax credit carryforwards expiration year		2026