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Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract] |  |  |  |  |
Cash received as collateral for derivative assets |  |  | $ 85 |  |
Fair value of securities pledged as collateral for derivative assets |  |  | (2) |  |
Other Comprehensive Income (Loss), before Reclassifications, before Tax |  |  |  | $ (602) | $ (25)
De-designated Interest swaps |  |  | 7,000 |  |
Total Impact to risk management hedging income |  |  | (130) |  |
Impact to risk management hedging income | $ (39) | $ (91) |  |  |
Amortized - probable cashflows in OCI |  |  | (177) |  |
Amoritized Off Market Element |  |  | 170 |  |
Price alignment income |  | 51 | 46 | 51 | $ 8
Allowance for credit losses on lending-related commitments |  | 40 | 35 | 40 |
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit |  | 38 | $ 30 | 38 |
Final year of expiration for outstanding letters of credit |  |  | 2035 |  |
Risk participation agreements covering standby and commercial letters of credit |  | 85 | $ 223 | 85 |
Standby and commercial letters of credit outstanding |  | 3,600 | 4,200 | 3,600 |
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities |  | 34 | 34 | 34 |
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities |  | 32 | 29 | 32 |
Allowance for credit losses on lending-related commitments, unused commitments to extend credit |  | 2 | 5 | 2 |
Notional Amount of Derivative Credit Risk Participation Agreements |  | 1,000 | 1,100 | 1,000 |
Maximum estimated exposure to credit risk participation agreements assuming 100% default |  | $ 2 | $ 1 | $ 2 |
Weighted average remaining maturity of credit risk participation agreements, in years |  |  | 4 years 7 months 6 days |  |
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position |  |  | $ 0 |  |
Fair value of securities pledged as collateral for derivative liabilities |  |  | $ 143 |  |

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- Definition The total value of cash collateral received from counterparties to secure the fair value of derivative contracts in an unrealized gain position. Includes both the amount offset against derivative assets under master netting arrangements as well as cash collateral that has not been offset. + References No definition available. + Details
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- Definition Average period covered by credit risk derivative contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4K -Subparagraph (a)(1) -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K + Details
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- Definition The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4H + Details
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