Credit Quality and the Allowance for Loan and Lease Losses - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Financing Receivable, Allowance for Credit Losses
Mortgage loans in process of foreclosure amount	$ 162		$ 110
Financing receivable, excluding accrued interest, modified in period, amount	$ 362	$ 254
Loan modification program, percentage of modifications to total portfolio	0.21%	0.21%
Loan modification program, loans excluded from modification program	$ 22	$ 19
Unfunded commitment amounts	160		$ 69
Commercial
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 334	$ 224
Loan modification program, percentage of modifications to total portfolio	0.28%	0.31%
Commercial \| Minimum
Financing Receivable, Allowance for Credit Losses
Term extension period	3 months
Commercial \| Maximum
Financing Receivable, Allowance for Credit Losses
Term extension period	12 months
Residential Mortgage
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 16	$ 18
Loan modification program, percentage of modifications to total portfolio	0.08%	0.10%
Modification program option, in-process modifications	$ 44	$ 3
Consumer
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 12	$ 12
Loan modification program, percentage of modifications to total portfolio	0.04%	0.04%
Consumer \| Home equity
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 5	$ 4
Loan modification program, percentage of modifications to total portfolio	0.07%	0.09%

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