Related Party Transactions - Summary of Loans (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
HSBC Finance Corporation [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 3,014,000,000	$ 3,015,000,000
HMUS [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	563,000,000	199,000,000
HSBC Bank Brasil [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	1,108,000,000	1,000,000,000
Other Affiliates [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	136,000,000	1,114,000,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 4,821,000,000	$ 5,328,000,000