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Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2024 | Dec. 31, 2023
Derivative [Line Items] |  |
Notional Amount | $ 27,277 | $ 26,977
Fair Value Hedges [Member] |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | 104 | 43
Fair Value Hedges [Member] | Forward-Starting Interest Rate Swap Agreements [Member] |  |
Derivative [Line Items] |  |
Notional Amount | 1,800 | 1,000
Cash Flow Hedges [Member] |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | 361 | 214
Cash Flow Hedges [Member] | Forward-Starting Interest Rate Swap Agreements [Member] |  |
Derivative [Line Items] |  |
Notional Amount | $ 6,000 | $ 9,000

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