Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended	36 Months Ended
		Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2017	Dec. 31, 2007
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss		$ 56,739		$ 66,721	$ 56,739
Carrying value of swap		4,252,577		4,135,130	4,252,577
Carrying value		358		627	358
Collateral accepted under security resale agreements, fair value		25,969		30,784	25,969
Collateral accepted under security repurchase agreements but not reported on the balance sheet that can be sold or repledged, fair value		23,329		29,835	23,329
Collateral accepted under security repurchase agreements that has been sold or repledged under repurchase agreements or to cover short sales		7,373		769	7,373
HSBC Securities [Member]
Guarantor Obligations [Line Items]
Whole loan securitization						$ 24,000
Securities available-for-sale [Member]
Guarantor Obligations [Line Items]
Securities pledged as collateral that can be sold or repledged by the secured party, fair value		3,680		892	3,680
Trading Securities [Member]
Guarantor Obligations [Line Items]
Securities pledged as collateral that can be sold or repledged by the secured party, fair value		3,889		2,772	3,889
Financial standby letters of credit, net of participations [Member]
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss	[1],[2]	4,961		5,423	4,961
Carrying value	[1],[2]	0		0	0
Performance (non-financial) guarantees, net of participations [Member]
Guarantor Obligations [Line Items]
Notional/maximum exposure to loss	[1],[2]	2,995		2,969	2,995
Carrying value	[1],[2]	0		0	0
Obligation to Repurchase Receivables Sold [Member]
Guarantor Obligations [Line Items]
Outstanding repurchase demands		3		6	3
Mortgage Securitization Activity Related Litigation [Member] | HSBC Securities [Member]
Guarantor Obligations [Line Items]
Mortgage securitization outstanding loan purchase and sold		4,400		4,600	4,400
Other liabilities [Member]
Guarantor Obligations [Line Items]
Allowance for credit losses on unfunded standby letters of credit		23		39	23
Other liabilities [Member] | Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Deferred fees on standby letters of credit		$ 49		$ 49	49
Visa Class B Shares [Member]
Guarantor Obligations [Line Items]
Shares sold (shares)		1,230,039	1,161,897	638,219
Other Income (Loss) [Member] | Visa Class B Shares [Member]
Guarantor Obligations [Line Items]
Gain on sale of shares sold		$ 166		$ 71	312
Swap [Member]
Guarantor Obligations [Line Items]
Carrying value of swap		50		$ 14	50
Carrying value of swap related to sale during the first half of 2017		$ 35			$ 35

[1] 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.

[2] Includes $1,340 million and $1,315 million of both financial and performance standby letters of credit issued for the benefit of HSBC affiliates at June 30, 2017 and December 31, 2016, respectively.