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 (Detail) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Carrying Value		$ (201)	$ (627)
Notional/maximum exposure to loss		53,675	66,721
Credit derivatives [Member]
Guarantor Obligations [Line Items]
Carrying Value	[1],[2]	(201)	(627)
Notional/maximum exposure to loss	[1],[2]	45,228	58,329
Financial standby letters of credit, net of participations [Member]
Guarantor Obligations [Line Items]
Carrying Value	[3],[4]	0	0
Notional/maximum exposure to loss	[3],[4]	5,190	5,423
Performance standby letters of credit, net of participations [Member]
Guarantor Obligations [Line Items]
Carrying Value	[3],[4]	0	0
Notional/maximum exposure to loss	[3],[4]	$ 3,257	$ 2,969

[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.

[3] For standby letters of credit, maximum loss represents losses to be recognized assuming the letters of credit have been fully drawn and the obligors have defaulted with zero recovery.

[4] Includes $1,270 million and $1,315 million of both financial and performance standby letters of credit issued for the benefit of HSBC affiliates at September 30, 2017 and December 31, 2016, respectively.