LOANS AND LEASES - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | ||||
|---|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Dec. 31, 2025 |
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| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||||
| Accrued interest receivable on loans and leases held for investment | $ 832 | $ 825 | |||
| Loans pledged as collateral for FHLB borrowed funds | [1] | 141,709 | 140,749 | ||
| Interest income on direct financing lease | 12 | $ 11 | |||
| Retail | Residential mortgages | Federal Home Loan Bank Advances | |||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||||
| Loans pledged as collateral for FHLB borrowed funds | 42,500 | 40,800 | |||
| Consumer and Commercial Portfolio Segment | Education, commercial and industrial, and commercial real estate loans | Notes Payable, Other Payables | |||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||||
| Loans pledged as collateral for FHLB borrowed funds | $ 24,000 | $ 19,000 | |||
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