Related Party Transactions - Summary of Loans (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
HSBC Finance Corporation [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 3,014	$ 3,014
HMUS [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	334	563
HSBC Bank Brasil [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	1,108	1,108
Other Affiliates [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	151	136
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 4,607	$ 4,821