v3.26.3
Borrowings - Financing VIEs (Detail) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Securities Financing Transaction [Line Items]    
Short-term borrowings $ 5,751 $ 5,073
Long-term borrowings 37,429 40,633
Total 43,180 45,706
Total assets 46,128 48,681
Total Before Hedge Accounting Adjustments [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 5,759 5,074
Long-term borrowings 37,626 40,672
Total 43,385 45,746
Hedge Accounting Adjustments [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings (8) (1)
Long-term borrowings (197) (39)
Total (205) (40)
Assets and Liabilities of Consolidated Variable Interest Entities [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 4,842 4,389
Long-term borrowings 32,960 35,835
Total 37,802 40,224
Loans 40,194 42,190
Cash 1,284 1,466
Other assets 1,322 1,300
Total assets 42,800 44,956
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | FFELP Loan Securitizations [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 0 109
Long-term borrowings 22,637 25,302
Total 22,637 25,411
Loans 23,198 25,942
Cash 762 950
Other assets 1,092 1,096
Total assets 25,052 27,988
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Private Education Loan Securitizations [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 384 469
Long-term borrowings 9,953 10,250
Total 10,337 10,719
Loans 11,735 11,960
Cash 352 364
Other assets 152 127
Total assets 12,239 12,451
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | FFELP Loan ABCP Facilities [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 2,349 1,869
Long-term borrowings 376 299
Total 2,725 2,168
Loans 2,657 2,115
Cash 77 84
Other assets 142 108
Total assets 2,876 2,307
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Private Education Loan ABCP Facilities [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 2,109 1,942
Long-term borrowings 0 0
Total 2,109 1,942
Loans 2,557 2,173
Cash 93 68
Other assets 31 44
Total assets 2,681 2,285
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Personal Loan A B C P Facilities [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 0  
Long-term borrowings 40  
Total 40  
Loans 47  
Cash 0  
Other assets 0  
Total assets 47  
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Total Before Hedge Accounting Adjustments [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 4,842 4,389
Long-term borrowings 33,006 35,851
Total 37,848 40,240
Loans 40,194 42,190
Cash 1,284 1,466
Other assets 1,417 1,375
Total assets 42,895 45,031
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Hedge Accounting Adjustments [Member]    
Securities Financing Transaction [Line Items]    
Short-term borrowings 0 0
Long-term borrowings (46) (16)
Total (46) (16)
Loans 0 0
Cash 0 0
Other assets (95) (75)
Total assets $ (95) $ (75)