Related Party Transactions - Summary of Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Assets:
Cash and due from banks	$ 1,155		$ 961		$ 1,238	$ 1,359
Interest bearing deposits with banks	23,466		19,614
Trading assets	27,336		28,894
Loans	68,897		67,695		62,932
Other assets	7,567		8,140
Total assets	187,174	[1]	185,487	[1]	189,385
Liabilities:
Deposits	105,531		112,608		117,049
Trading liabilities	9,349		10,875
Short-term borrowings	28,767		19,135
Long-term debt	22,953		22,847
Other	3,907		3,558
Total liabilities	170,507	[1]	169,023	[1]
Parent And Other Subsidiaries Of Common Parent [Member]
Assets:
Cash and due from banks	106		102
Interest bearing deposits with banks	921	[2]	631	[2]
Trading assets	15,995	[3]	17,082	[3]
Loans	5,277		5,328
Other assets	1,050	[4]	1,219	[4]
Total assets	23,349		24,362
Liabilities:
Deposits	13,518		16,936
Trading liabilities	17,833	[3]	19,463	[3]
Short-term borrowings	1,712		1,514
Long-term debt	3,988		3,987
Other	617	[4]	573	[4]
Total liabilities	$ 37,668		$ 42,473

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities (“VIEs”) as of March 31, 2014 and December 31, 2013 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. Assets: Interest bearing deposits with banks, $3 million and $5 million, Securities held-to-maturity, $180 million and $200 million Other assets $479 million and $502 million. Total assets $662 million and $707 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $80 million and $93 million. Total liabilities $172 million and $185 million, respectively.

[2] Includes interest bearing deposits with HSBC Mexico S.A. of $800 million and $500 million at March 31, 2014 and December 31, 2013, 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.