Related Party Transactions Related Parties - Summary of Assets (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Due from Affiliates	$ 5,854	$ 4,514
HSBC Finance Corporation [Member]
Related Party Transaction [Line Items]
Due from Affiliates	3,015	2,019
HMUS [Member]
Related Party Transaction [Line Items]
Due from Affiliates	929	310
HSBC Bank Brasil [Member]
Related Party Transaction [Line Items]
Due from Affiliates	1,000	1,000
HSBC Panama [Member] | Extended Uncommitted Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Due from Affiliates	200	372
Other Affiliates [Member]
Related Party Transaction [Line Items]
Due from Affiliates	$ 710	$ 813