Loans - Loan Payment Modifications by Type of Modification (Details) - Commercial loans - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Modified [Line Items]
Loans modified	$ 14	$ 65
% of Total Loans	0.00%	0.20%
Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	$ 14	$ 65
% of Total Loans	0.10%	0.20%
Interest Rate Reduction
Financing Receivable, Modified [Line Items]
Loans modified	$ 0	$ 0
Interest Rate Reduction \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	0	0
Principal Forgiveness
Financing Receivable, Modified [Line Items]
Loans modified	0	0
Principal Forgiveness \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	0	0
Term Extension / Significant Payment Deferral
Financing Receivable, Modified [Line Items]
Loans modified	14	65
Term Extension / Significant Payment Deferral \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	14	65
Combination
Financing Receivable, Modified [Line Items]
Loans modified	0	0
Combination \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Loans modified	$ 0	$ 0

Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

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- Definition

Percentage, excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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