Retained Earnings and Regulatory Capital Requirements - Capital Amounts and Ratios in Accordance With Current Banking Regulations (Parenthetical) (Details) (USD $)	Jun. 30, 2014
Banking and Thrift [Abstract]
Consolidated assets under tier one common capital	$ 50,000,000,000

Well Capitalized Tier One Common Ratio For Entities With At Least Fifty Billion Assets

No definition available.

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