Commitments and Contingencies - Additional Information (Details)						1 Months Ended					3 Months Ended
	Feb. 10, 2021	Sep. 04, 2020	Apr. 02, 2020	Apr. 09, 2019	Jan. 01, 2017 USD ($)	Feb. 28, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020	Feb. 28, 2019 USD ($)	Jul. 31, 2016 USD ($) ft²	Mar. 31, 2022 USD ($) ft² extensionOption	Mar. 31, 2021 USD ($)	Nov. 30, 2020 ft²	Apr. 30, 2018 ft²
Commitments And Contingencies [Line Items]
Operating lease, cost											$ 1,800,000	$ 1,700,000
Operating lease, payments											1,800,000	1,800,000
Increase (decrease) in purchase commitments											(773,000)	(8,945,000)
Inventory adjustments to previous reserves											3,200,000
Total remaining contract costs											4,700,000
Contract cost incurred in research and development activities											211,900,000
Supply Agreement, Patheon Inc.
Commitments And Contingencies [Line Items]
Minimum purchase commitment											3,900,000
BioVectra Inc
Commitments And Contingencies [Line Items]
Long-term minimum purchase commitment renewal term		1 year
Cost of purchased minimum quantity product											83,600,000
Siegfried Evionnaz SA
Commitments And Contingencies [Line Items]
Cost of purchased minimum quantity product											$ 13,500,000
Purchase commitment, option to extend, prior notice period											12 months
Esteve Química, S.A
Commitments And Contingencies [Line Items]
Initial term of supply agreement				4 years
Long-term minimum purchase commitment											$ 39,000,000
STA Pharmaceutical Hong Kong Limited
Commitments And Contingencies [Line Items]
Long-term minimum purchase commitment											$ 77,900,000
Minimum purchase commitment, initial term			4 years
WuXi STA
Commitments And Contingencies [Line Items]
Purchase commitment, option to extend, prior notice period	18 months
Minimum purchase commitment, initial term	4 years
Long-term purchase commitment, fixed price, period	12 months
Long-term purchase commitment, option to terminate, prior notice period (at least)	180 days
Minimum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term											6.65%
Operating lease, remaining lease term											4 years 5 months 12 days
Maximum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term											7.25%
Operating lease, remaining lease term											9 years 4 months 2 days
Keryx Biopharmaceuticals, Inc.
Commitments And Contingencies [Line Items]
Preliminary fair value of the off-market element							$ 76,700,000				$ 72,700,000
Cambridge
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²										45,362			65,167
Annual lease expense										$ 242,000
Monthly lease expense					$ 22,000
Cambridge | Letter of Credit | Other Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease											$ 1,600,000
Cambridge | Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²														19,805
Monthly lease expense							$ 48,000		$ 135,000
Operating lease, free monthly rent, period								2 months
Lease period, number of extension options | extensionOption											1
Lease extension period											5 years
Boston | Keryx Biopharmaceuticals, Inc. | Letter of Credit | Other Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease											$ 1,400,000
Boston | Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²											27,300
Monthly lease expense						$ 200,122					$ 136,000
Operating lease, free monthly rent, period						5 months
Operating lease, annual rent escalation, percentage						2.00%
Operating lease, allowance for leasehold improvements						$ 1,954,680
Boston | Office Space | Keryx Biopharmaceuticals, Inc.
Commitments And Contingencies [Line Items]
Lease period, number of extension options | extensionOption											1
Lease extension period											5 years
Sublease rental income											$ 500,000	$ 400,000