Related Party Transactions - Summary of Related Party Transactions (Details) - USD ($) $ in Millions		Sep. 30, 2015		Dec. 31, 2014		Sep. 30, 2014		Dec. 31, 2013
Assets:
Cash and due from banks		$ 914		$ 891		$ 1,013		$ 961
Interest bearing deposits with banks		22,300		30,807
Securities purchased under agreements to resell		20,423		1,413
Trading assets		15,652		21,092
Loans		84,942		77,741		73,439
Other assets		8,013		7,989
Total assets		204,366	[1]	185,539	[1]	175,012
Liabilities:
Deposits		131,450	[1],[2]	116,118	[1]	$ 108,677	[2]
Trading liabilities	[1]	6,336		8,164
Short-term borrowings	[1]	8,948		12,795
Long-term debt	[1]	33,018		27,524
Other	[1]	3,794		3,971
Total liabilities	[1]	183,546		168,572
HSBC Mexico [Member]
Related Party Transaction [Line Items]
Extended loans and lines of credit		1,200		1,200
Affiliated Entity [Member]
Assets:
Cash and due from banks		250		140
Interest bearing deposits with banks		362		928
Securities purchased under agreements to resell	[3]	5,500		0
Trading assets	[4]	21,274		20,194
Loans		5,447		4,821
Other assets	[5]	517		983
Total assets		33,350		27,066
Liabilities:
Deposits		21,898		16,596
Trading liabilities	[4]	20,691		21,130
Short-term borrowings		1,811		847
Long-term debt		1,825		3,981
Other	[5]	846		459
Total liabilities		$ 47,071		$ 43,013

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") as of September 30, 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 $338 million and $380 million. Total assets $338 million and $380 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $69 million and $75 million. Total liabilities $161 million and $167 million, respectively.

[2] During the second quarter of 2015, we concluded that brokered deposits would be better presented as debt under the Group Reporting Basis. As a result, we reclassified $2.1 billion of brokered deposits in the GB&M segment to debt at September 30, 2014 to conform with current year presentation.

[3] Reflects overnight purchases of U.S. Treasury securities which HSBC Securities (USA) Inc. ("HSI") has agreed to repurchase.

[4] 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.

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