Loans - Summary of the Financial Effect of Loan Payment Modifications (Details) $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($)
Commercial loans \| Real estate, including construction
Financing Receivable, Modified [Line Items]
Weighted-Average Interest Rate Reduction	0.00%
Weighted-Average Term Extension / Payment Deferral (in years)	3 months 18 days
Commercial loans \| Real estate, including construction \| Principal Forgiven
Financing Receivable, Modified [Line Items]
Principal Forgiven (in millions)	$ 0
Commercial loans \| Business and corporate banking
Financing Receivable, Modified [Line Items]
Weighted-Average Interest Rate Reduction	0.50%
Weighted-Average Term Extension / Payment Deferral (in years)	1 year 6 months
Commercial loans \| Business and corporate banking \| Principal Forgiven
Financing Receivable, Modified [Line Items]
Principal Forgiven (in millions)	$ 2
Commercial loans \| Global banking
Financing Receivable, Modified [Line Items]
Weighted-Average Interest Rate Reduction	0.00%
Weighted-Average Term Extension / Payment Deferral (in years)	1 year 7 months 6 days
Commercial loans \| Global banking \| Principal Forgiven
Financing Receivable, Modified [Line Items]
Principal Forgiven (in millions)	$ 0
Consumer loans \| Residential mortgages
Financing Receivable, Modified [Line Items]
Weighted-Average Interest Rate Reduction	3.90%
Weighted-Average Term Extension / Payment Deferral (in years)	1 year 8 months 12 days
Consumer loans \| Residential mortgages \| Principal Forgiven
Financing Receivable, Modified [Line Items]
Principal Forgiven (in millions)	$ 0

Amount of increase (decrease) in amortized cost excluding accrued interest, of financing receivable modified for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
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-Section 50
-Paragraph 42
-Subparagraph (a)(1)
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-URI https://asc.fasb.org//1943274/2147481962/310-10-50-42

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-42

Reference 3: http://www.xbrl.org/2003/role/exampleRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481962/310-10-50-34

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Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

+ References

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-SubTopic 10
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-Section 55
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Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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