Related Party Transactions - Summary of Loans (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
HSBC Finance Corporation [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties		$ 2,501	$ 3,014
HMUS [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties		563	978
Extended loans and lines of credit		5,900	10,700
HSBC Mexico [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties		195	725
Extended loans and lines of credit		1,200	1,200
Regency [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties	[1]	0	58
Other Affiliates [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties		15	40
Extended loans and lines of credit		3,100
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Loans and leases receivable from related parties		$ 3,274	$ 4,815

[1] An asset-backed commercial paper conduit consolidated by an HSBC affiliate.