v3.26.1
CREDIT QUALITY AND THE ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Loss (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Allowance for Loan and Lease Losses [Roll Forward]      
Allowance for loan and lease losses, beginning of period $ 1,943 $ 2,061 $ 2,061
Charge-offs (183) (234)  
Recoveries 45 34  
Net charge-offs (138) (200)  
Provision expense (benefit) for loans and leases 153 153  
Allowance for loan and lease losses, end of period 1,958 2,014 1,943
Unfunded lending commitments [Roll Forward]      
Allowance for unfunded lending commitments, beginning of period 240 198 198
Provision expense (benefit) for unfunded lending commitments (13) 0  
Allowance for unfunded lending commitments, end of period 227 198 240
Total allowance for credit losses, end of period 2,185 2,212  
Commercial      
Allowance for Loan and Lease Losses [Roll Forward]      
Allowance for loan and lease losses, beginning of period 1,058 1,140 1,140
Charge-offs (91) (85)  
Recoveries 18 4  
Net charge-offs (73) (81)  
Provision expense (benefit) for loans and leases 130 89  
Allowance for loan and lease losses, end of period 1,115 1,148 1,058
Unfunded lending commitments [Roll Forward]      
Allowance for unfunded lending commitments, beginning of period 194 155 155
Provision expense (benefit) for unfunded lending commitments (5) 9  
Allowance for unfunded lending commitments, end of period 189 164 194
Total allowance for credit losses, end of period 1,304 1,312  
Retail      
Allowance for Loan and Lease Losses [Roll Forward]      
Allowance for loan and lease losses, beginning of period 885 921 921
Charge-offs (92) (149)  
Recoveries 27 30  
Net charge-offs (65) (119)  
Provision expense (benefit) for loans and leases 23 64  
Allowance for loan and lease losses, end of period 843 866 885
Unfunded lending commitments [Roll Forward]      
Allowance for unfunded lending commitments, beginning of period 46 43 43
Provision expense (benefit) for unfunded lending commitments (8) (9)  
Allowance for unfunded lending commitments, end of period 38 34 $ 46
Total allowance for credit losses, end of period $ 881 $ 900