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Derivatives and Hedging Activities - Cumulative Basis Adjustments on Fair Value Hedges (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Securities available for sale | $ 37,185 | $ 39,117
Long-term debt | Interest rate |  |
Derivatives, Fair Value [Line Items] |  |
Carrying amount of hedged item | 9,919 | 10,411
Hedge accounting basis adjustment | (437) | (552)
Securities available for sale | Interest rate |  |
Derivatives, Fair Value [Line Items] |  |
Carrying amount of hedged item | 8,655 | 405
Hedge accounting basis adjustment | (152) | 48
Securities available for sale | 13,000 | 708
Hedged layer amount | 7,000 | 405
Hedged asset portfolio layer method cumulative basis adjustments | (147) | 48
Not Designated as Hedging Instrument | Long-term debt | Interest rate |  |
Derivatives, Fair Value [Line Items] |  |
Hedge accounting basis adjustment | $ (5) | $ (6)

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- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
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- Definition Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 181 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480401/815-10-55-181 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EE -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4EE + Details
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