Related Party Transactions - Additional Information (Detail) - USD ($)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Due to affiliates		$ 802,000,000		$ 3,300,000,000
Long-term debt		4,320,000,000		4,340,000,000
Notional values of derivative contracts		1,765,000,000		1,765,000,000
Derivative related liabilities		46,000,000		12,000,000
Fair value of our agreements with affiliate counterparties required the affiliate to provide collateral		274,000,000		317,000,000
Interest bearing deposits with banks		0		1,500,000,000
Derivative related expense		2,000,000	$ (115,000,000)
HSBC USA, Inc. [Member]
Related Party Transaction [Line Items]
Due to affiliates		0		2,500,000,000
HSBC USA, Inc. [Member] | Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Borrowing capacity of credit facility		$ 5,000,000,000
Debt instrument, term		364 days
Maximum maturity period for borrowings		5 years
Repayments of Lines of Credit		$ 2,500,000,000
Loss on extinguishment of debt		28,000,000
HSBC Holdings plc [Member]
Related Party Transaction [Line Items]
Due to affiliates		802,000,000		800,000,000
HSBC North America [Member] | Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Borrowing capacity of credit facility		$ 1,000,000,000		1,000,000,000
Debt instrument, term		364 days
Amount of credit facility outstanding		$ 0		0
HSBC affiliates [Member]
Related Party Transaction [Line Items]
Due to affiliates	[1]	802,000,000		3,300,000,000
Interest bearing deposits with banks		0		1,500,000,000
HSBC Securities (USA) Inc. [Member]
Related Party Transaction [Line Items]
Receivable transaction assistance fees		5,000,000	0
HSBC Bank USA [Member]
Related Party Transaction [Line Items]
Notional values of derivative contracts		1,800,000,000		1,800,000,000
Receivables services to affiliates		$ 93,000,000		559,000,000
Series C Preferred Stock [Member]
Related Party Transaction [Line Items]
Number of shares of stock issued (shares)		1,000
Dividend paid on preferred stock		$ 22,000,000	$ 22,000,000
Subordinated Debt [Member] | Public Subordinated Debt Issue Maturing 2021 [Member]
Related Party Transaction [Line Items]
Long-term debt		3,000,000,000
Visa Class B Shares [Member] | HSBC USA, Inc. [Member]
Related Party Transaction [Line Items]
Notional values of derivative contracts		58,000,000		50,000,000
Derivative related liabilities		6,000,000		$ 5,000,000
Discontinued Operations [Member]
Related Party Transaction [Line Items]
Derivative related expense		$ (1,000,000)

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