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Investment Securities (Summary Of Investment Securities) (Details) $ in Millions | Dec. 31, 2023 USD ($) security | Dec. 31, 2022 USD ($) security
--- | --- | ---
Investment securities available-for-sale, Amortized Cost | $ 19,541 | $ 22,045
Investment securities available-for-sale, Gross Unrealized Gains | 0 | 0
Investment securities available-for-sale, Gross Unrealized Losses | 2,672 | 3,033
Investment securities available-for-sale, Fair Value | 16,869 | 19,012
Debt Securities, Available-for-Sale, Unrealized Loss Position | 16,867 | 19,010
Temporarily Impaired Total, Unrealized Losses | $ 2,672 | $ 3,033
Debt Securities Count | security | 1,250 | 1,289
Temporarily Impaired Less than 12 Months, Fair Value | $ 10 | $ 8,504
Temporarily Impaired, Less than 12 Months, Unrealized Losses | 0 | 771
Temporarily Impaired 12 Months or more, Fair Value | 16,857 | 10,506
Temporarily Impaired, 12 Months or more, Unrealized Losses | 2,672 | 2,262
U.S. Treasury and other U.S. government agency securities |  |
Investment securities available-for-sale, Amortized Cost | 1,681 | 2,810
Investment securities available-for-sale, Gross Unrealized Gains | 0 | 0
Investment securities available-for-sale, Gross Unrealized Losses | 76 | 146
Investment securities available-for-sale, Fair Value | 1,605 | 2,664
Debt Securities, Available-for-Sale, Unrealized Loss Position | 1,605 | 2,664
Temporarily Impaired Total, Unrealized Losses | $ 76 | $ 146
Debt Securities Count | 19 | 27
Temporarily Impaired Less than 12 Months, Fair Value | $ 0 | $ 996
Temporarily Impaired 12 Months or more, Fair Value | 1,605 | 1,668
Temporarily Impaired, 12 Months or more, Unrealized Losses | 76 | 141
Residential mortgage-backed securities |  |
Investment securities available-for-sale, Amortized Cost | 12,607 | 13,983
Investment securities available-for-sale, Gross Unrealized Gains | 0 | 0
Investment securities available-for-sale, Gross Unrealized Losses | 2,088 | 2,328
Investment securities available-for-sale, Fair Value | 10,519 | 11,655
Debt Securities, Available-for-Sale, Unrealized Loss Position | 10,517 | 11,653
Temporarily Impaired Total, Unrealized Losses | $ 2,088 | $ 2,328
Debt Securities Count | 978 | 1,008
Temporarily Impaired Less than 12 Months, Fair Value | $ 10 | $ 3,500
Temporarily Impaired 12 Months or more, Fair Value | 10,507 | 8,153
Temporarily Impaired, 12 Months or more, Unrealized Losses | 2,088 | 1,967
Commercial Mortgage Backed Securities |  |
Investment securities available-for-sale, Amortized Cost | 5,253 | 5,252
Investment securities available-for-sale, Gross Unrealized Gains | 0 | 0
Investment securities available-for-sale, Gross Unrealized Losses | 508 | 559
Investment securities available-for-sale, Fair Value | 4,745 | 4,693
Debt Securities, Available-for-Sale, Unrealized Loss Position | 4,745 | 4,693
Temporarily Impaired Total, Unrealized Losses | $ 508 | $ 559
Debt Securities Count | 253 | 254
Temporarily Impaired Less than 12 Months, Fair Value | $ 0 | $ 4,008
Temporarily Impaired 12 Months or more, Fair Value | 4,745 | 685
Temporarily Impaired, 12 Months or more, Unrealized Losses | $ 508 | $ 154

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