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Debt Securities (Schedule Of Amortized Cost, Gross Unrealized Gains And Losses, And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity) (Details) - USD ($) $ in Millions | Sep. 30, 2023 | Dec. 31, 2022
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Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | $ 30,353 | $ 31,367
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (4,125) | (3,435)
Available-for-sale debt securities, net carrying value | 26,228 | 27,933
Debt securities available for sale | 26,228 | 27,933
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities held to maturity, amortized cost | 772 | 812
Held To Maturity Debt Securities Gross Unrealized Gains | 0 | 0
Held To Maturity Debt Securities Gross Unrealized Losses | (9) | (11)
Debt Securities held to maturity | 763 | 801
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain | 0 | 0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss | (60) | (50)
Debt Securities held to maturity, estimated fair value | 703 | 751
US Treasury Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 1,316 | 1,310
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (130) | (123)
Available-for-sale debt securities, net carrying value | 1,186 | 1,187
Debt securities available for sale | 1,186 | 1,187
Federal agency securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 1,087 | 898
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (83) | (62)
Available-for-sale debt securities, net carrying value | 1,004 | 836
Debt securities available for sale | 1,004 | 836
US States and Political Subdivisions Debt Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 2 | 2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 0 | 0
Available-for-sale debt securities, net carrying value | 2 | 2
Debt securities available for sale | 2 | 2
Residential Agency [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 18,802 | 19,477
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (3,062) | (2,523)
Available-for-sale debt securities, net carrying value | 15,740 | 16,954
Debt securities available for sale | 15,740 | 16,954
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities held to maturity, amortized cost | 255 | 289
Held To Maturity Debt Securities Gross Unrealized Gains | 0 | 0
Held To Maturity Debt Securities Gross Unrealized Losses | (8) | (10)
Debt Securities held to maturity | 247 | 279
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain | 0 | 0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss | (28) | (21)
Debt Securities held to maturity, estimated fair value | 219 | 258
Residential Non-Agency [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost |  | 1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax |  | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax |  | 0
Available-for-sale debt securities, net carrying value |  | 1
Debt securities available for sale |  | 1
Commercial Agency [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 7,934 | 8,262
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (776) | (649)
Available-for-sale debt securities, net carrying value | 7,158 | 7,613
Debt securities available for sale | 7,158 | 7,613
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities held to maturity, amortized cost | 517 | 523
Held To Maturity Debt Securities Gross Unrealized Gains | 0 | 0
Held To Maturity Debt Securities Gross Unrealized Losses | (1) | (1)
Debt Securities held to maturity | 516 | 522
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Gain | 0 | 0
Held-to-maturity Debt Securities, Accumulated Unrecognized Holding Loss | (32) | (29)
Debt Securities held to maturity, estimated fair value | 484 | 493
Commercial Non Agency [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 93 | 198
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (15) | (12)
Available-for-sale debt securities, net carrying value | 78 | 186
Debt securities available for sale | 78 | 186
Corporate and other debt securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 1,119 | 1,219
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 | 1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | (59) | (66)
Available-for-sale debt securities, net carrying value | 1,060 | 1,154
Debt securities available for sale | $ 1,060 | $ 1,154

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