Summary of Significant Accounting Policies and New Accounting Pronouncements - Charge-Off and Nonaccrual Policies and Practices (Details)	12 Months Ended
Dec. 31, 2013
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of days contractually delinquent	90 days
Consumer Loans [Member] \| Residential Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of days contractually delinquent	3 months
Period of consecutive payments	6 months
Delinquent threshold period	6 months
Update period	180 days
Valuation Period from Fair Value Determination Date	90 days
Consumer Loans [Member] \| Credit Card Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Delinquent threshold period	6 months
Notification period	60 days
Delinquent threshold period	180 days
Consumer Loans [Member] \| Other consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Delinquent threshold period	4 months

Loans and Leases Receivable, Nonaccrual Status, Accrual Status Resumed, Period of Consecutive Payments

No definition available.

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Loans and Leases Receivable, Nonaccrual Status, Delinquent Threshold Period

No definition available.

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Loans and Leases Receivable, Write-offs, Bankruptcy, Delinquent Threshold Period

No definition available.

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Loans and Leases Receivable, Write-offs, Bankruptcy, Notification Period

No definition available.

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Loans and Leases Receivable, Write-offs, Delinquent Threshold Period

No definition available.

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Data Type:	xbrli:durationItemType
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Loans and Leases Receivable, Write-offs, Fair Value Determination, Update Period

No definition available.

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Loans and Leases Receivable, Write-offs, Valuation Period from Fair Value Determination Date

No definition available.

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Namespace Prefix:	husi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration