Related Party Transactions - Summary of Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
Assets:
Cash and due from banks	$ 972		$ 891		$ 1,155	$ 961
Interest bearing deposits with banks	32,249		30,807
Trading assets	22,444		21,092
Loans	81,458		77,741		68,897
Other assets	8,657		7,989
Total assets	201,594	[1]	185,539	[1]	187,174
Liabilities:
Deposits	119,094		116,118		105,531
Trading liabilities	11,288		8,164
Short-term borrowings	15,653		12,795
Long-term debt	29,420		27,524
Other	5,068		3,971
Total liabilities	180,523	[1]	168,572	[1]
HSBC Mexico [Member]
Assets:
Interest bearing deposits with banks	800
Affiliated Entity [Member]
Assets:
Cash and due from banks	171		140
Interest bearing deposits with banks	1,017	[2]	928	[2]
Trading assets	21,048	[3]	20,194	[3]
Loans	5,016		4,821
Other assets	1,082	[4]	983	[4]
Total assets	28,334		27,066
Liabilities:
Deposits	15,688		16,596
Trading liabilities	22,478	[3]	21,130	[3]
Short-term borrowings	1,676		847
Long-term debt	0		3,981
Other	387	[4]	459	[4]
Total liabilities	$ 40,229		$ 43,013

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") as of March 31, 2015 and December 31, 2014 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 216, "Variable Interest Entities," for additional information. Assets: Other assets $372 million and $380 million. Total assets $372 million and $380 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $86 million and $75 million. Total liabilities $178 million and $167 million, respectively.

[2] Includes interest bearing deposits with HSBC Mexico S.A. of $800 million at both March 31, 2015 and December 31, 2014, respectively.

[3] Trading assets and trading liabilities do not reflect the impact of netting which allows the offsetting of amounts relating to certain contracts if certain conditions are met. Trading assets and liabilities primarily consist of derivatives contracts.

[4] Other assets and other liabilities primarily consist of derivative contracts.