Related Party Transactions - Summary of Related Party Transactions (Details) - USD ($) $ in Millions		Sep. 30, 2016		Dec. 31, 2015		Sep. 30, 2015	Dec. 31, 2014
Assets:
Cash and due from banks		$ 903		$ 968		$ 914	$ 891
Interest bearing deposits with banks		17,139		7,478
Securities purchased under agreements to resell		30,714		19,847
Trading assets		19,586		17,085
Loans		77,625		82,917		84,942
Other assets		5,531		6,890
Total assets		208,310	[1]	188,278	[1]	204,366
Liabilities:
Deposits		131,082		118,579		131,450
Trading liabilities		7,537		7,455
Short-term borrowings		6,062		4,995
Long-term debt		39,500		33,509
Other		3,152		3,215
Total liabilities	[1]	187,333		167,753
Affiliated Entity [Member]
Assets:
Cash and due from banks		133		169
Interest bearing deposits with banks		26		244
Securities purchased under agreements to resell	[2]	4,000		4,000
Trading assets	[3]	17,305		18,632
Loans		4,463		4,815		$ 5,447
Other assets	[4]	203		458
Total assets		26,130		28,318
Liabilities:
Deposits		20,130		13,486
Trading liabilities	[3]	18,391		19,496
Short-term borrowings		2,134		2,004
Long-term debt		5,832		1,827
Other	[4]	277		346
Total liabilities		$ 46,764		$ 37,159

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at September 30, 2016 and December 31, 2015 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. Assets: Other assets $248 million and $320 million. Total assets $248 million and $320 million respectively. Liabilities: Long-term debt $79 million and $92 million, Interest, taxes and other liabilities $55 million and $68 million. Total liabilities $134 million and $160 million, respectively.

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

[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 balances associated with hedging activities and other miscellaneous account receivables and payables.