Related Party Transactions - Related Party Balances and Income and (Expense) Generated by Related Party Transactions (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash		$ 128	$ 124
Interest bearing deposits with banks		1,500	0
Securities purchased under agreements to resell		2,392	2,724
Other assets		427	208
Total assets		13,882	24,145
Liabilities
Due to affiliates		3,300	5,925
Other liabilities		610	1,773
Total liabilities		$ 8,448	17,510
General term of securities purchased under an agreement to resell		120 days
Income/(Expense):
Servicing and other fees from HSBC affiliates		$ 1	20	$ 28
Support services from HSBC affiliates		(158)	(224)	(271)
HSBC affiliates [Member]
Assets:
Cash		128	124
Interest bearing deposits with banks		1,500	0	2,000
Securities purchased under agreements to resell	[1]	2,392	2,724
Other assets		114	128
Total assets		4,134	2,976
Liabilities
Due to affiliates	[2]	3,300	5,925
Other liabilities		41	62
Total liabilities		3,341	5,987
Income/(Expense):
Interest income from HSBC affiliates		6	6	6
Interest expense paid to HSBC affiliates	[3]	(225)	(302)	(307)
Net interest income (expense)		(219)	(296)	(301)
Servicing and other fees from HSBC affiliates		1	20	28
Support services from HSBC affiliates		(158)	(224)	(271)
Stock based compensation expense with HSBC	[4]	(2)	(4)	(5)
Borrowings [Member] | HSBC affiliates [Member]
Income/(Expense):
Gain (loss) on FVO debt with affiliate		$ 10	$ 17	$ (16)

[1] Securities under an agreement to resell are purchased from HSBC Securities (USA) Inc. and generally have terms of 120 days or less. The collateral underlying the securities purchased under agreements to resell, however, is with an unaffiliated third party. Interest income recognized on these securities is reflected as interest income from HSBC affiliate in the table below.

[2] Due to affiliates includes amounts owed to HSBC and its subsidiaries as a result of direct debt issuances and excludes preferred stock.

[3] Includes interest expense paid to HSBC affiliates for debt held by HSBC affiliates as well as net interest paid to or received from HSBC affiliates on risk management hedges related to non-affiliated debt.

[4] Employees may participate in one or more stock compensation plans sponsored by HSBC. These expenses are included in Salaries and employee benefits in our consolidated statement of income (loss). Certain employees are also eligible to participate in a defined benefit pension plan and other postretirement benefit plans sponsored by HSBC North America which are discussed in Note 15, "Pension and Other Postretirement Benefits"