Loans - Delinquency Ratio for Consumer Loan (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Loans Receivable, Net [Abstract]
Residential mortgage loan delinquency carried at lower of amortized cost or fair value less cost to sell	$ 1,041	$ 1,074

Residential mortgage loan delinquency carried at lower of amortized cost or fair value less cost to sell.

No definition available.

Name:	husi_ResidentialMortgageLoanDelinquencyCarriedAtLowerOfAmortizedCostOrFairValueLessCostToSell
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant