v3.26.1
Debt - Schedule of Debt (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Mar. 31, 2024
Debt Instrument [Line Items]        
Total, before unamortized debt issuance costs, premiums and discounts $ 1,827,413,000   $ 1,830,629,000  
Less: unamortized debt issuance costs, premiums and discounts (13,932,000)   (15,467,000)  
Total debt 1,813,481,000   1,815,162,000  
Debt discounts issued 0      
Amount not available for general borrowing purposes to secure letter of credit 4,100,000   4,700,000  
Asset Pledged as Collateral        
Debt Instrument [Line Items]        
Amount not available for general borrowing purposes to secure letter of credit $ 46,700,000   46,700,000  
Minimum        
Debt Instrument [Line Items]        
Unused commitment fee percentage 0.00%      
Maximum        
Debt Instrument [Line Items]        
Unused commitment fee percentage 0.50%      
Convertible notes | Convertible senior notes, due 2026        
Debt Instrument [Line Items]        
Stated Interest Rate 0.00%      
Total, before unamortized debt issuance costs, premiums and discounts $ 428,022,000   428,022,000  
Less: unamortized debt issuance costs, premiums and discounts (1,000,000.0)   (1,500,000)  
Interest expense $ 500,000 $ 500,000    
Effective interest rate 0.43% 0.43%    
Net carrying amount $ 427,000,000.0   426,600,000  
Convertible notes | Convertible senior notes, due 2029        
Debt Instrument [Line Items]        
Stated Interest Rate 1.25%     1.25%
Total, before unamortized debt issuance costs, premiums and discounts $ 862,500,000   862,500,000  
Less: unamortized debt issuance costs, premiums and discounts (12,900,000)   (14,000,000.0)  
Interest expense $ 3,800,000 $ 3,800,000    
Effective interest rate 1.77% 1.77%    
Net carrying amount $ 849,600,000   848,500,000  
Contractual interest expense 2,700,000 $ 2,700,000    
Amortization of discounts and issuance costs 1,100,000 $ 1,100,000    
Other financing | Other financing        
Debt Instrument [Line Items]        
Total Collateral 261,983,000      
Total Capacity 314,927,000      
Total, before unamortized debt issuance costs, premiums and discounts 0   0  
Other financing | Other financing | Loans at fair value        
Debt Instrument [Line Items]        
Total Collateral 59,500,000      
Other financing | Other financing | Securities Investment        
Debt Instrument [Line Items]        
Total Collateral 202,500,000      
Student loan securitizations        
Debt Instrument [Line Items]        
Total Collateral 59,786,000      
Total, before unamortized debt issuance costs, premiums and discounts $ 50,891,000   54,107,000  
Student loan securitizations | Minimum        
Debt Instrument [Line Items]        
Stated Interest Rate 3.09%      
Student loan securitizations | Maximum        
Debt Instrument [Line Items]        
Stated Interest Rate 3.73%      
Secured Debt | Asset Pledged as Collateral        
Debt Instrument [Line Items]        
Total Capacity $ 264,900,000      
Unsecured Debt        
Debt Instrument [Line Items]        
Total Capacity 50,000,000.0      
Personal loan warehouse facilities | Line of Credit        
Debt Instrument [Line Items]        
Total Collateral 0      
Total Capacity 3,700,000,000      
Total, before unamortized debt issuance costs, premiums and discounts $ 0   0  
Personal loan warehouse facilities | Line of Credit | Minimum        
Debt Instrument [Line Items]        
Stated Interest Rate 4.28%      
Personal loan warehouse facilities | Line of Credit | Maximum        
Debt Instrument [Line Items]        
Stated Interest Rate 4.91%      
Student loan warehouse facilities | Line of Credit        
Debt Instrument [Line Items]        
Total Collateral $ 0      
Total Capacity 3,480,000,000      
Total, before unamortized debt issuance costs, premiums and discounts $ 0   0  
Student loan warehouse facilities | Line of Credit | Minimum        
Debt Instrument [Line Items]        
Stated Interest Rate 4.18%      
Student loan warehouse facilities | Line of Credit | Maximum        
Debt Instrument [Line Items]        
Stated Interest Rate 4.83%      
Revolving credit facility | Line of Credit        
Debt Instrument [Line Items]        
Amount not available for general borrowing purposes to secure letter of credit $ 11,400,000      
Revolving credit facility | Revolving credit facility        
Debt Instrument [Line Items]        
Stated Interest Rate 5.26%      
Total Capacity $ 645,000,000      
Total, before unamortized debt issuance costs, premiums and discounts 486,000,000   486,000,000  
Less: unamortized debt issuance costs, premiums and discounts $ (900,000)   $ (1,000,000.0)