Derivative Instruments and Hedging Activities - Schedule of Effect of Hedging Derivative Instruments in the Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative [Line Items]
Loans, including fees	$ 1,361	$ 589	$ 3,931	$ 1,707
Investment securities	224	95	629	276
Deposits	561	294	1,616	852
FHLB advances and other borrowings	90	29	226	87
Loans, including fees \| Fair Value Hedges
Derivative [Line Items]
Recognized on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Pre-tax income (loss) recognized on cash flow hedges	0	0	0	0
Investment securities \| Fair Value Hedges
Derivative [Line Items]
Recognized on derivatives	41	(2)	33	(24)
Recognized on hedged items	(41)	2	(33)	24
Pre-tax income (loss) recognized on cash flow hedges	0	0	0	0
Deposits \| Fair Value Hedges
Derivative [Line Items]
Recognized on derivatives	(15)	0	(27)	0
Recognized on hedged items	15	0	27	0
Pre-tax income (loss) recognized on cash flow hedges	0	0	0	0
FHLB advances and other borrowings \| Fair Value Hedges
Derivative [Line Items]
Recognized on derivatives	(67)	2	(101)	19
Recognized on hedged items	67	(2)	101	(19)
Pre-tax income (loss) recognized on cash flow hedges	$ 0	$ 0	$ 0	$ 0

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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