Derivatives and Hedging Activities - Schedule of Cumulative Basis Adjustments on Fair Value Hedges (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Fair Value	$ 40,456	$ 37,707
Long-term debt \| Interest rate
Derivatives, Fair Value [Line Items]
Carrying amount of hedged item	9,436	10,249
Long-term debt \| Interest rate \| Hedge accounting basis adjustment - active hedges
Derivatives, Fair Value [Line Items]
Hedge accounting basis adjustment	(200)	(490)
Long-term debt \| Interest rate \| Hedge accounting basis adjustment - discontinued hedges
Derivatives, Fair Value [Line Items]
Hedge accounting basis adjustment	(4)	(4)
Securities Available for Sale \| Interest rate
Derivatives, Fair Value [Line Items]
Carrying amount of hedged item	12,407	12,097
Fair Value	6,100	5,000
Hedged layer amount	4,500	4,000
Hedged asset, fair value hedge, portfolio layer method, hedged layer, fair value, cumulative increase (decrease)	(44)	41
Securities Available for Sale \| Interest rate \| Hedge accounting basis adjustment - active hedges
Derivatives, Fair Value [Line Items]
Hedge accounting basis adjustment	(113)	5
Hedged asset, fair value hedge, portfolio layer method, hedged layer, fair value, cumulative increase (decrease)	(59)	24
Securities Available for Sale \| Interest rate \| Hedge accounting basis adjustment - discontinued hedges
Derivatives, Fair Value [Line Items]
Hedge accounting basis adjustment	15	17
Hedged asset, fair value hedge, portfolio layer method, hedged layer, fair value, cumulative increase (decrease)	$ 15	$ 17

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).

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Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk. Excludes cumulative basis adjustment related to foreign exchange risk.

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Amount of liability hedged in fair value hedging relationship.

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