Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements - Additional Information (Detail) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss		$ 53,675	$ 66,721
Credit derivatives [Member]
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss	[1],[2]	45,228	58,329
Affiliated Entity [Member] | Credit derivatives [Member]
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss		26,541	29,999
Affiliated Entity [Member] | Financial and performance standby letters of credit [Member]
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss		$ 1,270	$ 1,315

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

[2] Includes $26,541 million and $29,999 million of notional issued for the benefit of HSBC affiliates at September 30, 2017 and December 31, 2016, respectively.