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Debt Securities (Narrative) (Details) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) security	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Debt Securities Transferred from Available for Sale to Held to Maturity, Amortized Cost	$ 2,000	$ 1,000
Debt securities available for sale				$ 26,886		$ 26,224
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security				1,405		1,722
Unrealized gains (losses) on securities available for sale:
Debt Securities, Available-for-sale [Line Items]
OCIDebtSecuritiesAvailableForSaleUnrealizedGainLossTransferredToHeldToMaturityArisingDuringBeforeTax	$ 74	$ 153	$ 436	$ 227	$ 436
Asset Pledged as Collateral
Debt Securities, Available-for-sale [Line Items]
Debt securities available for sale				$ 21,000		$ 20,900

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