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Loans - Loan Payment Modifications by Type of Modification (Details) - Commercial loans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Financing Receivable, Modified [Line Items]
Loans modified	$ 121	$ 129	$ 249	$ 139
% of Total Loans	0.30%	0.30%	0.60%	0.30%
Commercial mortgages
Financing Receivable, Modified [Line Items]
Loans modified	$ 84		$ 101
% of Total Loans	8.90%		10.70%
Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	$ 37	$ 129	$ 148	$ 139
% of Total Loans	0.10%	0.40%	0.50%	0.50%
Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Loans modified	$ 0	$ 23	$ 0	$ 23
Interest Rate Reduction \| Commercial mortgages
Financing Receivable, Modified [Line Items]
Loans modified	0		0
Interest Rate Reduction \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	0	23	0	23
Principal Forgiveness
Financing Receivable, Modified [Line Items]
Loans modified	0	0	0	0
Principal Forgiveness \| Commercial mortgages
Financing Receivable, Modified [Line Items]
Loans modified	0		0
Principal Forgiveness \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	0	0	0	0
Term Extension / Significant Payment Deferral
Financing Receivable, Modified [Line Items]
Loans modified	101	103	229	113
Term Extension / Significant Payment Deferral \| Commercial mortgages
Financing Receivable, Modified [Line Items]
Loans modified	84		101
Term Extension / Significant Payment Deferral \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	17	103	128	113
Combination
Financing Receivable, Modified [Line Items]
Loans modified	20	3	20	3
Combination \| Commercial mortgages
Financing Receivable, Modified [Line Items]
Loans modified	0		0
Combination \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	$ 20	$ 3	$ 20	$ 3