Revenue and Deferred Revenue (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
	Feb. 09, 2021	Nov. 30, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Contract revenue			$ 1,648	$ 371
Deferred revenue, current			$ 653		$ 2,301
License
Disaggregation of Revenue [Line Items]
Contract termination period, curable breach			60 days
Contract termination period, incurable breach			90 days
Vifor Pharma | License
Disaggregation of Revenue [Line Items]
Upfront and near-term milestone payment, entitled to receive		$ 60,000
Contract with customer, liability		30,000
Equity securities	$ 30,000
Post-approval milestone payment, entitled to receive		260,000
Sales-related milestone payment, entitled to receive		1,585,000
Total milestone payment, entitled to receive		$ 1,905,000
Royalty rates (up to)		40.00%
Transaction price, percent of upfront payment		50.00%
Contract revenue			$ 1,600	$ 400
Deferred revenue, current			700		$ 2,300
Vifor Pharma | License | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-11-06
Disaggregation of Revenue [Line Items]
Transaction price at inception of license agreement		$ 15,000
Performance period		2 years 2 months 12 days
Vifor Pharma | License | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Disaggregation of Revenue [Line Items]
Transaction price at inception of license agreement			$ 15,000
Performance period			9 months
Vifor Pharma | License | IPO
Disaggregation of Revenue [Line Items]
Equity investment received	5,000
Vifor Pharma | License | Private placement
Disaggregation of Revenue [Line Items]
Equity investment received	$ 25,000