v3.26.1
LOANS, LEASES, AND ALLOWANCE FOR CREDIT LOSSES (Summary Aging Analysis, Modified) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total $ 608 $ 522
Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 584 492
Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 24 30
30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 15 22
90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 9 8
Commercial:    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 223 111
Commercial: | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 199 101
Commercial: | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 24 10
Commercial: | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 15 2
Commercial: | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 9 8
Commercial: | Commercial and industrial    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 195 86
Commercial: | Commercial and industrial | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 177 84
Commercial: | Commercial and industrial | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 18 2
Commercial: | Commercial and industrial | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 15 2
Commercial: | Commercial and industrial | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 3 0
Commercial: | Owner-occupied    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 28 17
Commercial: | Owner-occupied | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 22 17
Commercial: | Owner-occupied | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 6 0
Commercial: | Owner-occupied | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Commercial: | Owner-occupied | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 6 0
Commercial: | Municipal    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   8
Commercial: | Municipal | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   0
Commercial: | Municipal | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   8
Commercial: | Municipal | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   0
Commercial: | Municipal | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   8
Commercial real estate:    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 379 395
Commercial real estate: | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 379 375
Commercial real estate: | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 20
Commercial real estate: | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 20
Commercial real estate: | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Commercial real estate: | Term    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 374 347
Commercial real estate: | Term | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 374 339
Commercial real estate: | Term | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 8
Commercial real estate: | Term | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 8
Commercial real estate: | Term | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Commercial real estate: | Construction and land development    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 5 48
Commercial real estate: | Construction and land development | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 5 36
Commercial real estate: | Construction and land development | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 12
Commercial real estate: | Construction and land development | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 12
Commercial real estate: | Construction and land development | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer:    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 6 16
Consumer: | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 6 16
Consumer: | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | 1-4 family residential    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 5 14
Consumer: | 1-4 family residential | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 5 14
Consumer: | 1-4 family residential | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | 1-4 family residential | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | 1-4 family residential | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | Home equity credit line    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 1 1
Consumer: | Home equity credit line | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 1 1
Consumer: | Home equity credit line | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | Home equity credit line | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total 0 0
Consumer: | Home equity credit line | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total $ 0 0
Consumer: | Bankcard and other revolving plans    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   1
Consumer: | Bankcard and other revolving plans | Current    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   1
Consumer: | Bankcard and other revolving plans | Total past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   0
Consumer: | Bankcard and other revolving plans | 30-89 days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   0
Consumer: | Bankcard and other revolving plans | 90+ days past due    
Financing Receivable, Allowance for Credit Losses [Line Items]    
Total   $ 0