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INVESTMENT SECURITIES - Schedule of Fair Values and Unrealized Losses of Impaired Securities, by Length of Impairment (Details) $ in Millions | Sep. 30, 2025 USD ($) security | Dec. 31, 2024 USD ($) security
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Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 14 | 43
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 208 | 213
Debt securities, available-for-sale, number of positions | security | 222 | 256
Debt securities, available-for-sale, less than 12 months, fair value | $ 186 | $ 1,104
Debt securities, available-for-sale, 12 months or longer, fair value | 1,485 | 1,670
Debt securities, available-for-sale, fair value | 1,671 | 2,774
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | (10)
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (97) | (148)
Debt securities, available-for-sale, unrealized losses | $ (97) | $ (158)
U.S. Treasury |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security |  | 3
Debt securities, available-for-sale, 12 months or longer, number of positions | security |  | 2
Debt securities, available-for-sale, number of positions | security |  | 5
Debt securities, available-for-sale, less than 12 months, fair value |  | $ 74
Debt securities, available-for-sale, 12 months or longer, fair value |  | 75
Debt securities, available-for-sale, fair value |  | 149
Debt securities, available-for-sale, less than 12 months, unrealized losses |  | (1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses |  | 0
Debt securities, available-for-sale, unrealized losses |  | $ (1)
U.S. government agencies |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 7 | 6
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 10 | 12
Debt securities, available-for-sale, number of positions | security | 17 | 18
Debt securities, available-for-sale, less than 12 months, fair value | $ 12 | $ 11
Debt securities, available-for-sale, 12 months or longer, fair value | 19 | 25
Debt securities, available-for-sale, fair value | 31 | 36
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | 0
Debt securities, available-for-sale, 12 months or longer, unrealized losses | 0 | 0
Debt securities, available-for-sale, unrealized losses | $ 0 | $ 0
U.S. GSE |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 1 | 2
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 5 | 7
Debt securities, available-for-sale, number of positions | security | 6 | 9
Debt securities, available-for-sale, less than 12 months, fair value | $ 30 | $ 75
Debt securities, available-for-sale, 12 months or longer, fair value | 101 | 126
Debt securities, available-for-sale, fair value | 131 | 201
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | 0
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (1) | (2)
Debt securities, available-for-sale, unrealized losses | $ (1) | $ (2)
Agency MBS |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 2 | 9
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 92 | 92
Debt securities, available-for-sale, number of positions | security | 94 | 101
Debt securities, available-for-sale, less than 12 months, fair value | $ 50 | $ 235
Debt securities, available-for-sale, 12 months or longer, fair value | 276 | 355
Debt securities, available-for-sale, fair value | 326 | 590
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | (1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (9) | (19)
Debt securities, available-for-sale, unrealized losses | $ (9) | $ (20)
Agency CMO |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 0 | 0
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 65 | 66
Debt securities, available-for-sale, number of positions | security | 65 | 66
Debt securities, available-for-sale, less than 12 months, fair value | $ 0 | $ 0
Debt securities, available-for-sale, 12 months or longer, fair value | 626 | 698
Debt securities, available-for-sale, fair value | 626 | 698
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | 0
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (68) | (98)
Debt securities, available-for-sale, unrealized losses | $ (68) | $ (98)
Agency commercial MBS |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 3 | 23
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 24 | 20
Debt securities, available-for-sale, number of positions | security | 27 | 43
Debt securities, available-for-sale, less than 12 months, fair value | $ 90 | $ 709
Debt securities, available-for-sale, 12 months or longer, fair value | 435 | 359
Debt securities, available-for-sale, fair value | 525 | 1,068
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | (8)
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (17) | (27)
Debt securities, available-for-sale, unrealized losses | $ (17) | $ (35)
States of the U.S. and political subdivisions (municipals) |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 0 | 0
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 9 | 10
Debt securities, available-for-sale, number of positions | security | 9 | 10
Debt securities, available-for-sale, less than 12 months, fair value | $ 0 | $ 0
Debt securities, available-for-sale, 12 months or longer, fair value | 19 | 22
Debt securities, available-for-sale, fair value | 19 | 22
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | 0
Debt securities, available-for-sale, 12 months or longer, unrealized losses | (2) | (2)
Debt securities, available-for-sale, unrealized losses | $ (2) | $ (2)
Other debt securities |  |
Schedule Of Securities [Line Items] |  |
Debt securities, available-for-sale, less than 12 months, number of positions | security | 1 | 0
Debt securities, available-for-sale, 12 months or longer, number of positions | security | 3 | 4
Debt securities, available-for-sale, number of positions | security | 4 | 4
Debt securities, available-for-sale, less than 12 months, fair value | $ 4 | $ 0
Debt securities, available-for-sale, 12 months or longer, fair value | 9 | 10
Debt securities, available-for-sale, fair value | 13 | 10
Debt securities, available-for-sale, less than 12 months, unrealized losses | 0 | 0
Debt securities, available-for-sale, 12 months or longer, unrealized losses | 0 | 0
Debt securities, available-for-sale, unrealized losses | $ 0 | $ 0

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