Debt - Additional Information (Details)				3 Months Ended		9 Months Ended
	Jul. 15, 2022 USD ($)	Dec. 10, 2020 USD ($)	Nov. 11, 2019 USD ($) tranche	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Nov. 25, 2019 USD ($)
Line of Credit Facility [Line Items]
Term loan, net of facility fees, lender expenses and issuance costs				$ 65,947,000		$ 65,947,000
Loss on extinguishment of debt				906,000	$ 0	906,000	$ 0
Derivative liability				760,000		760,000		$ 1,820,000
Collateral Agent, Pharmakon
Line of Credit Facility [Line Items]
Derivative liability				800,000		800,000		$ 1,800,000
Term Loan | Collateral Agent, Pharmakon | Tranche A and B
Line of Credit Facility [Line Items]
Payment for debt prepayment	$ 25,000,000
Payment for debt prepayment premium, including accrued and unpaid interest	500,000
Loss on extinguishment of debt				900,000		900,000
Term Loan | Collateral Agent, Pharmakon | Tranche A
Line of Credit Facility [Line Items]
Payment for debt prepayment	5,000,000
Term Loan | Collateral Agent, Pharmakon | Tranche B
Line of Credit Facility [Line Items]
Payment for debt prepayment	$ 20,000,000
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 100,000,000
Line of credit, maximum borrowing capacity, number of available tranches | tranche			2
Term loan, maturity term			5 years
Term loan, principal payment						8,000,000
Term loan, maturity term, potential reduction (up to)			1 year
Term loan, amortization period, potential reduction (up to)			1 year
Facility fee percentage on principal amount			2.00%
Facility fee paid, amount			$ 2,000,000
Prepayment premium percentage on principal if prepaid prior to third anniversary of funding			2.00%
Prepayment premium percentage on principal if prepaid prior to fourth anniversary and after third anniversary of funding			1.00%
Prepayment premium percentage on principal if prepaid after fourth anniversary of funding			0.50%
Interest expense				$ 2,100,000	$ 2,700,000	$ 7,500,000	$ 8,100,000
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | Debt Instrument, Quarterly Periodic Payment, Period One
Line of Credit Facility [Line Items]
Term loan, first quarterly principal payment due in			33 months
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | Debt Instrument, Quarterly Periodic Payment, Period Two
Line of Credit Facility [Line Items]
Term loan, first quarterly principal payment due in			48 months
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | Three-month LIBOR
Line of Credit Facility [Line Items]
Basis spread on floating interest rate			7.50%
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | LIBOR
Line of Credit Facility [Line Items]
Debt instrument, floor rate			2.00%
Debt instrument, cap rate			3.35%
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | Tranche A
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 80,000,000
Term loan, net of facility fees, lender expenses and issuance costs									$ 77,300,000
Biopharma Credit Investments V (Master) LP | Keryx | Term Loan | Collateral Agent, Pharmakon | Tranche B
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 20,000,000
BPCR Limited Partnership | Keryx | Term Loan | Collateral Agent, Pharmakon | Tranche B
Line of Credit Facility [Line Items]
Proceeds from line of credit		$ 20,000,000