v3.26.1
FAIR VALUE - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Mar. 31, 2026
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale $ 31,790 $ 33,314
Marketable equity securities 127 130
Total derivative assets 534 498
Total derivative liabilities $ 494 448
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag [Extensible Enumeration] Total derivative liabilities  
U.S. Treasury    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale $ 10,673 12,442
Residential mortgage-backed securities    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 17,623 17,595
Commercial mortgage-backed securities    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 3,299 3,099
Municipal bonds    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 12 12
Fair Value, Recurring    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 31,790 33,314
Marketable equity securities 127 130
Loans held for sale 87 89
Loans 22 24
Total derivative assets 534 498
Total derivative liabilities 494 448
Fair Value, Recurring | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 534 498
Total derivative liabilities 494 448
Fair Value, Recurring | Interest rate contracts | Qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Interest rate contracts | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 385 356
Total derivative liabilities 381 366
Fair Value, Recurring | Foreign exchange contract | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 122 114
Total derivative liabilities 113 82
Fair Value, Recurring | Other derivative | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 27 28
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Marketable equity securities 50 50
Loans held for sale 0 0
Loans 0 0
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1 | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1 | Interest rate contracts | Qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1 | Interest rate contracts | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1 | Foreign exchange contract | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 1 | Other derivative | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 31,767 33,294
Marketable equity securities 77 80
Loans held for sale 87 89
Loans 22 24
Total derivative assets 505 467
Total derivative liabilities 494 448
Fair Value, Recurring | Level 2 | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 505 467
Total derivative liabilities 494 448
Fair Value, Recurring | Level 2 | Interest rate contracts | Qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 2 | Interest rate contracts | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 383 353
Total derivative liabilities 381 366
Fair Value, Recurring | Level 2 | Foreign exchange contract | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 122 114
Total derivative liabilities 113 82
Fair Value, Recurring | Level 2 | Other derivative | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 23 20
Marketable equity securities 0 0
Loans held for sale 0 0
Loans 0 0
Total derivative assets 29 31
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3 | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 29 31
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3 | Interest rate contracts | Qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3 | Interest rate contracts | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 2 3
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3 | Foreign exchange contract | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Fair Value, Recurring | Level 3 | Other derivative | Non-qualifying Hedges    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Total derivative assets 27 28
Total derivative liabilities 0 0
Fair Value, Recurring | U.S. Treasury    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 10,673 12,442
Fair Value, Recurring | U.S. Treasury | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | U.S. Treasury | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 10,673 12,442
Fair Value, Recurring | U.S. Treasury | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Government agency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 43 38
Fair Value, Recurring | Government agency | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Government agency | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 43 38
Fair Value, Recurring | Government agency | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Residential mortgage-backed securities    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 17,623 17,595
Fair Value, Recurring | Residential mortgage-backed securities | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Residential mortgage-backed securities | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 17,623 17,595
Fair Value, Recurring | Residential mortgage-backed securities | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Commercial mortgage-backed securities    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 3,299 3,099
Fair Value, Recurring | Commercial mortgage-backed securities | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Commercial mortgage-backed securities | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 3,299 3,099
Fair Value, Recurring | Commercial mortgage-backed securities | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Corporate bonds    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 140 128
Fair Value, Recurring | Corporate bonds | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Corporate bonds | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 117 108
Fair Value, Recurring | Corporate bonds | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 23 20
Fair Value, Recurring | Municipal bonds    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 12 12
Fair Value, Recurring | Municipal bonds | Level 1    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 0 0
Fair Value, Recurring | Municipal bonds | Level 2    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale 12 12
Fair Value, Recurring | Municipal bonds | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Investment securities available for sale $ 0 $ 0