v3.23.2
Debt - Narrative (Details)
 12 Months Ended
Jul. 15, 2022
USD ($)
Dec. 10, 2020
USD ($)
Nov. 11, 2019
USD ($)
tranche
Dec. 31, 2022
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Nov. 25, 2019
USD ($)
Line of Credit Facility [Line Items]              
Term loan, net of facility fees, lender expenses and issuance costs       $ 66,078,000      
Loss on extinguishment of debt       906,000 $ 0 $ 0  
Derivative liability       760,000 1,820,000    
Collateral Agent, Pharmakon              
Line of Credit Facility [Line Items]              
Derivative liability       800,000 1,800,000    
Term Loan | Collateral Agent, Pharmakon | Tranche A and B              
Line of Credit Facility [Line Items]              
Payment for debt prepayment premium, including accrued and unpaid interest $ 500,000            
Loss on extinguishment of debt       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 Limited Partner | 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        
Debt instrument, 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       $ 9,500,000 $ 10,900,000 $ 8,900,000  
Biopharma Credit Investments V Master Limited Partner | Keryx | Term Loan | Collateral Agent, Pharmakon | Debt Instrument, First 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 Limited Partner | Keryx | Term Loan | Collateral Agent, Pharmakon | Debt Instrument, First 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 Limited Partner | 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 Limited Partner | 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 Limited Partner | 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 Limited Partner | Keryx | Term Loan | Collateral Agent, Pharmakon | Tranche B              
Line of Credit Facility [Line Items]              
Line of credit, maximum borrowing capacity     $ 20,000,000        
Proceeds from line of credit   $ 20,000,000