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INVESTMENT SECURITIES (Summary of Investment Securities) (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Amortized cost |  |
Available-for-sale | $ 10,379 | $ 10,601
Held-to-maturity | 9,059 | 9,669
Total investment securities | 19,438 | 20,270
Gross unrealized gains |  |
Available-for-sale | 19 | 1
Held-to-maturity | 89 | 2
Total investment securities | 108 | 3
Gross unrealized losses |  |
Available-for-sale | 1,228 | 1,507
Held-to-maturity | 42 | 289
Estimated fair value |  |
Available-for-sale | 9,170 | 9,095
Held-to-maturity, Estimated fair value | 9,106 | 9,382
Total investment securities | 18,276 | 18,477
Total investment securities | 1,270 | 1,796
U.S. Treasury securities |  |
Amortized cost |  |
Available-for-sale | 1,401 | 781
Gross unrealized gains |  |
Available-for-sale | 15 | 0
Gross unrealized losses |  |
Available-for-sale | 105 | 119
Estimated fair value |  |
Available-for-sale | 1,311 | 662
Agency securities |  |
Amortized cost |  |
Available-for-sale | 349 | 441
Held-to-maturity | 139 | 148
Gross unrealized gains |  |
Available-for-sale | 0 | 0
Held-to-maturity | 0 | 0
Gross unrealized losses |  |
Available-for-sale | 17 | 26
Held-to-maturity | 4 | 8
Estimated fair value |  |
Available-for-sale | 332 | 415
Held-to-maturity, Estimated fair value | 135 | 140
Agency guaranteed mortgage-backed securities |  |
Amortized cost |  |
Available-for-sale | 7,208 | 7,713
Held-to-maturity | 8,643 | 9,202
Gross unrealized gains |  |
Available-for-sale | 4 | 1
Held-to-maturity | 89 | 2
Gross unrealized losses |  |
Available-for-sale | 1,041 | 1,263
Held-to-maturity | 28 | 263
Estimated fair value |  |
Available-for-sale | 6,171 | 6,451
Held-to-maturity, Estimated fair value | 8,704 | 8,941
Small Business Administration loan-backed securities |  |
Amortized cost |  |
Available-for-sale | 374 | 455
Gross unrealized gains |  |
Available-for-sale | 0 | 0
Gross unrealized losses |  |
Available-for-sale | 16 | 21
Estimated fair value |  |
Available-for-sale | 358 | 434
Municipal securities |  |
Amortized cost |  |
Available-for-sale | 1,022 | 1,186
Held-to-maturity | 277 | 319
Gross unrealized gains |  |
Available-for-sale | 0 | 0
Held-to-maturity | 0 | 0
Gross unrealized losses |  |
Available-for-sale | 49 | 78
Held-to-maturity | 10 | 18
Estimated fair value |  |
Available-for-sale | 973 | 1,108
Held-to-maturity, Estimated fair value | 267 | 301
Other debt securities |  |
Amortized cost |  |
Available-for-sale | 25 | 25
Gross unrealized gains |  |
Available-for-sale | 0 | 0
Gross unrealized losses |  |
Available-for-sale | 0 | 0
Estimated fair value |  |
Available-for-sale | 25 | 25
Available-for-sale, Unrealized Gains, Other | Maximum |  |
Gross unrealized gains |  |
Available-for-sale | $ 1 | $ 1

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