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ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Pretax and After-tax Components of Other Comprehensive Income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |
AOCI activity before reclassification, net amount | $ 45 | $ 224 |
Amounts reclassified from AOCI to earnings, net amount | 1 | 20 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, gross amount | 62 | 330 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, tax | (16) | (86) |
Other comprehensive income (loss), net of tax | 46 | 244 | $ (745)
Unrealized loss on securities available for sale: |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |
AOCI activity before reclassification, gross amount | (10) | 194 |
AOCI activity before reclassification, tax | 3 | (51) |
AOCI activity before reclassification, net amount | (7) | 143 |
Amounts reclassified from AOCI to earnings, gross amount | 0 | 26 |
Amounts reclassified from AOCI to earnings, tax | 0 | (7) |
Amounts reclassified from AOCI to earnings, net amount | 0 | 19 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, gross amount | (10) | 220 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, tax | 3 | (58) |
Other comprehensive income (loss), net of tax | (7) | 162 |
Unrealized loss on securities available for sale transferred to held to maturity |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |
AOCI activity before reclassification, net amount | 0 | 0 |
Amounts reclassified from AOCI to earnings, gross amount | 1 | 1 |
Amounts reclassified from AOCI to earnings, tax | 0 | 0 |
Amounts reclassified from AOCI to earnings, net amount | 1 | 1 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, gross amount | 1 | 1 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, tax | 0 | 0 |
Other comprehensive income (loss), net of tax | 1 | 1 |
Defined benefit pension items |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |
AOCI activity before reclassification, gross amount | 60 | 109 |
AOCI activity before reclassification, tax | (16) | (28) |
AOCI activity before reclassification, net amount | 44 | 81 |
Amounts reclassified from AOCI to earnings, net amount | 0 | 0 |
Other comprehensive income (loss), net of tax | 44 | 81 |
Unrealized gain on cash flow hedge derivatives |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |
AOCI activity before reclassification, gross amount | 11 | 0 |
AOCI activity before reclassification, tax | (3) | 0 |
AOCI activity before reclassification, net amount | 8 | 0 |
Amounts reclassified from AOCI to earnings, gross amount | 0 | 0 |
Amounts reclassified from AOCI to earnings, tax | 0 | 0 |
Amounts reclassified from AOCI to earnings, net amount | 0 | 0 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, gross amount | 11 | 0 |
Other comprehensive (loss) income on securities available for sale and cash flow hedges, tax | (3) | 0 |
Other comprehensive income (loss), net of tax | $ 8 | $ 0 |

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