v3.24.1.u1
Borrowings - Financing VIEs (Details) - USD ($)
$ in Thousands
Mar. 31, 2024
Dec. 31, 2023
Mar. 31, 2023
Debt Outstanding      
Short-Term $ 0 $ 0  
Long-Term 4,976,882 5,227,512  
Total 4,976,882 5,227,512  
Carrying Amount of Assets Securing Debt Outstanding      
Restricted Cash 147,809 149,669 $ 181,764
Other Assets 58,930 52,342  
Total assets 28,277,282 29,169,468  
Variable Interest Entity, Primary Beneficiary      
Debt Outstanding      
Short-Term 0 0  
Long-Term 3,983,877 4,235,312  
Total 3,983,877 4,235,312  
Carrying Amount of Assets Securing Debt Outstanding      
Loans 5,279,994 5,539,964  
Restricted Cash 147,649 149,412  
Other Assets 300,468 312,763  
Total assets 5,728,111 6,002,139  
Variable Interest Entity, Primary Beneficiary | Private Education Loan term securitizations      
Debt Outstanding      
Short-Term 0 0  
Long-Term 3,983,877 4,235,312  
Total 3,983,877 4,235,312  
Carrying Amount of Assets Securing Debt Outstanding      
Loans 5,279,994 5,539,964  
Restricted Cash 147,649 149,412  
Other Assets 300,115 311,697  
Total assets 5,727,758 6,001,073  
Variable Interest Entity, Primary Beneficiary | Secured Borrowing Facility      
Debt Outstanding      
Short-Term 0 0  
Long-Term 0 0  
Total 0 0  
Carrying Amount of Assets Securing Debt Outstanding      
Loans 0 0  
Restricted Cash 0 0  
Other Assets 353 1,066  
Total assets $ 353 $ 1,066