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Investment Securities - Schedule of Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Millions | Sep. 30, 2022 | Dec. 31, 2021
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Investment securities available for sale |  |
Investment securities available for sale, cost | $ 10,083 | $ 9,215
Investment securities available for sale, gross unrealized gains | 0 | 45
Investment securities available for sale, gross unrealized losses | (995) | (57)
Investment securities available for sale | 9,088 | 9,203
Investment in marketable equity securities |  |
Investment in marketable equity securities at cost | 73 | 73
Investment in marketable equity, gross unrealized gains | 20 | 25
Investment in marketable equity, gross unrealized losses | (1) | 0
Investment in marketable equity, fair value | 92 | 98
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 9,661 | 3,809
Investment securities held to maturity, gross unrealized gains | 0 | 6
Investment securities held to maturity, gross unrealized losses | (1,495) | (56)
Investment securities held to maturity, cost, fair value | 8,166 | 3,759
Total investment securities |  |
Total investment securities, amortized cost | 19,817 | 13,097
Total investment securities, gross unrealized gains | 20 | 76
Total investment securities, gross unrealized losses | (2,491) | (113)
Total investment securities, fair value | 17,346 | 13,060
U.S. Treasury |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 2,047 | 2,007
Investment securities available for sale, gross unrealized gains | 0 | 0
Investment securities available for sale, gross unrealized losses | (147) | (2)
Investment securities available for sale | 1,900 | 2,005
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 473 |
Investment securities held to maturity, gross unrealized gains | 0 |
Investment securities held to maturity, gross unrealized losses | (54) |
Investment securities held to maturity, cost, fair value | 419 |
Government agency |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 175 | 221
Investment securities available for sale, gross unrealized gains | 0 | 1
Investment securities available for sale, gross unrealized losses | (2) | (1)
Investment securities available for sale | 173 | 221
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 1,546 |
Investment securities held to maturity, gross unrealized gains | 0 |
Investment securities held to maturity, gross unrealized losses | (196) |
Investment securities held to maturity, cost, fair value | 1,350 |
Residential mortgage-backed securities |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 5,450 | 4,757
Investment securities available for sale, gross unrealized gains | 0 | 8
Investment securities available for sale, gross unrealized losses | (666) | (36)
Investment securities available for sale | 4,784 | 4,729
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 4,510 | 2,322
Investment securities held to maturity, gross unrealized gains | 0 | 6
Investment securities held to maturity, gross unrealized losses | (765) | (22)
Investment securities held to maturity, cost, fair value | 3,745 | 2,306
Commercial mortgage-backed securities |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 1,828 | 1,648
Investment securities available for sale, gross unrealized gains | 0 | 9
Investment securities available for sale, gross unrealized losses | (155) | (17)
Investment securities available for sale | 1,673 | 1,640
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 2,834 | 1,485
Investment securities held to maturity, gross unrealized gains | 0 | 0
Investment securities held to maturity, gross unrealized losses | (437) | (34)
Investment securities held to maturity, cost, fair value | 2,397 | 1,451
Corporate bonds |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 583 | 582
Investment securities available for sale, gross unrealized gains | 0 | 27
Investment securities available for sale, gross unrealized losses | (25) | (1)
Investment securities available for sale | 558 | 608
Supranational securities |  |
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 295 |
Investment securities held to maturity, gross unrealized gains | 0 |
Investment securities held to maturity, gross unrealized losses | (43) |
Investment securities held to maturity, cost, fair value | 252 |
Other |  |
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 3 | 2
Investment securities held to maturity, gross unrealized gains | 0 | 0
Investment securities held to maturity, gross unrealized losses | 0 | 0
Investment securities held to maturity, cost, fair value | $ 3 | $ 2

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