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Investment Securities - Schedule of Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Investment securities available for sale |  |
Investment securities available for sale, cost | $ 9,955 | $ 9,967
Investment securities available for sale, gross unrealized gains | 3 | 1
Investment securities available for sale, gross unrealized losses | (897) | (973)
Investment securities available for sale | 9,061 | 8,995
Investment in marketable equity securities |  |
Investment in marketable equity securities at cost | 75 | 75
Investment in marketable equity, gross unrealized gains | 14 | 21
Investment in marketable equity, gross unrealized losses | (4) | (1)
Investment in marketable equity, fair value | 85 | 95
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 10,381 | 10,279
Investment securities held to maturity, gross unrealized gains | 3 | 0
Investment securities held to maturity, gross unrealized losses | (1,391) | (1,484)
Investment securities held to maturity, cost, fair value | 8,993 | 8,795
Investments, Fair Value Disclosure [Abstract] |  |
Total investment securities, amortized cost | 20,411 | 20,321
Total investment securities, gross unrealized gains | 20 | 22
Total investment securities, gross unrealized losses | (2,292) | (2,458)
Total investment securities, fair value | 18,139 | 17,885
Investment securities available for sale, allowance for credit loss | 4 |
U.S. Treasury |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 2,091 | 2,035
Investment securities available for sale, gross unrealized gains | 0 | 0
Investment securities available for sale, gross unrealized losses | (113) | (137)
Investment securities available for sale | 1,978 | 1,898
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 475 | 474
Investment securities held to maturity, gross unrealized gains | 0 | 0
Investment securities held to maturity, gross unrealized losses | (42) | (50)
Investment securities held to maturity, cost, fair value | 433 | 424
Government agency |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 152 | 164
Investment securities available for sale, gross unrealized gains | 0 | 0
Investment securities available for sale, gross unrealized losses | (2) | (2)
Investment securities available for sale | 150 | 162
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 1,550 | 1,548
Investment securities held to maturity, gross unrealized gains | 0 | 0
Investment securities held to maturity, gross unrealized losses | (163) | (186)
Investment securities held to maturity, cost, fair value | 1,387 | 1,362
Residential mortgage-backed securities |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 5,415 | 5,424
Investment securities available for sale, gross unrealized gains | 3 | 1
Investment securities available for sale, gross unrealized losses | (570) | (630)
Investment securities available for sale | 4,848 | 4,795
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 4,511 | 4,605
Investment securities held to maturity, gross unrealized gains | 2 | 0
Investment securities held to maturity, gross unrealized losses | (655) | (723)
Investment securities held to maturity, cost, fair value | 3,858 | 3,882
Commercial mortgage-backed securities |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 1,755 | 1,774
Investment securities available for sale, gross unrealized gains | 0 | 0
Investment securities available for sale, gross unrealized losses | (170) | (170)
Investment securities available for sale | 1,585 | 1,604
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 3,547 | 3,355
Investment securities held to maturity, gross unrealized gains | 1 | 0
Investment securities held to maturity, gross unrealized losses | (497) | (484)
Investment securities held to maturity, cost, fair value | 3,051 | 2,871
Corporate bonds |  |
Investment securities available for sale |  |
Investment securities available for sale, cost | 542 | 570
Investment securities available for sale, gross unrealized gains | 0 | 0
Investment securities available for sale, gross unrealized losses | (42) | (34)
Investment securities available for sale | 500 | 536
Supranational securities |  |
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 296 | 295
Investment securities held to maturity, gross unrealized gains | 0 | 0
Investment securities held to maturity, gross unrealized losses | (34) | (41)
Investment securities held to maturity, cost, fair value | 262 | 254
Other |  |
Investment securities held to maturity |  |
Investment securities held to maturity, cost | 2 | 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 | $ 2 | $ 2

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