Guarantee Arrangements and Pledged Assets and Collateral - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Guarantor Obligations [Line Items]
Notional/Maximum Exposure to Loss	$ 127,512		$ 128,894
Credit derivatives [Member]
Guarantor Obligations [Line Items]
Notional/Maximum Exposure to Loss	115,685	[1],[2]	117,768	[1],[2]
Financial standby letters of credit, net of participations [Member]
Guarantor Obligations [Line Items]
Notional/Maximum Exposure to Loss	6,174	[3],[4]	5,358	[3],[4]
Affiliated Entity [Member] | Credit derivatives [Member]
Guarantor Obligations [Line Items]
Notional/Maximum Exposure to Loss	32,035		32,688
Affiliated Entity [Member] | Financial standby letters of credit, net of participations [Member]
Guarantor Obligations [Line Items]
Notional/Maximum Exposure to Loss	$ 880		$ 937

[1] Includes $32,035 million and $32,688 million of notional issued for the benefit of HSBC affiliates at March 31, 2015 and December 31, 2014, respectively.

[2] For credit derivatives, the maximum loss is represented by the notional amounts without consideration of mitigating effects from collateral or recourse arrangements.

[3] Includes $880 million and $937 million issued for the benefit of HSBC affiliates at March 31, 2015 and December 31, 2014, respectively.

[4] For standby letters of credit and liquidity asset purchase agreements, maximum loss represents losses to be recognized assuming the letter of credit and liquidity facilities have been fully drawn and the obligors have defaulted with zero recovery.