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INVESTMENT SECURITIES - Schedule of Amortized Cost and Fair Value of Securities Held to Maturity (Details) - USD ($) $ in Millions | Jun. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | $ 4,115 | $ 3,979
Gross Unrealized Gains | 16 | 3
Gross Unrealized Losses | (274) | (338)
Fair Value | 3,857 | 3,644
U.S. Treasury |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 1 | 1
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Fair Value | 1 | 1
U.S. GSE |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 30 | 29
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Fair Value | 30 | 29
Agency MBS |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 826 | 901
Gross Unrealized Gains | 2 | 1
Gross Unrealized Losses | (69) | (96)
Fair Value | 759 | 806
Agency CMO |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 664 | 714
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (74) | (95)
Fair Value | 590 | 619
Agency commercial MBS |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 1,597 | 1,326
Gross Unrealized Gains | 14 | 2
Gross Unrealized Losses | (25) | (44)
Fair Value | 1,586 | 1,284
States of the U.S. and political subdivisions (municipals) |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 985 | 992
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (105) | (103)
Fair Value | 880 | 889
Other debt securities |  |
Investment Securities Held To Maturity [Line Items] |  |
Amortized Cost | 12 | 16
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (1) | 0
Fair Value | $ 11 | $ 16

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