v3.26.1
Allowance for Loan Losses - Education Loans - Loan Type (Detail) - FFELP Loans [Member] - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Financing Receivable Recorded Investment Past Due [Line Items]    
Total loans, gross $ 26,738 $ 29,800
Change (3,062)  
Stafford Loans [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total loans, gross 8,825 9,703
Change (878)  
Consolidation Loans [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total loans, gross 15,201 17,077
Change (1,876)  
Rehab Loans [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total loans, gross 2,712 $ 3,020
Change $ (308)