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	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative [Line Items]
Loans, including fees	$ 1,310	$ 570	$ 2,570	$ 1,118
Investment securities	208	94	405	181
Deposits	534	285	1,055	558
FHLB advances and other borrowings	77	29	136	59
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	(2)	(5)	(8)	(22)
Recognized on hedged items	2	5	8	22
Pre-tax income (loss) recognized on cash flow hedges	0	0	0	0
Deposits \| Fair Value Hedges
Derivative [Line Items]
Recognized on derivatives	(7)	0	(12)	0
Recognized on hedged items	7	0	12	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	(21)	5	(34)	17
Recognized on hedged items	21	(5)	34	(17)
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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