Related Party Transactions - Summary of Related Party Transactions (Details) (USD $)	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Assets:
Cash and due from banks	$ 1,311,000,000		$ 1,359,000,000			$ 1,528,000,000	$ 1,616,000,000
Interest bearing deposits with banks	29,820,000,000		13,279,000,000
Trading assets	27,448,000,000		35,995,000,000
Loans	66,705,000,000		63,258,000,000		56,064,000,000
Other assets	8,765,000,000		7,069,000,000
Total assets	192,386,000,000	[1]	196,567,000,000	[1]	200,427,000,000
Liabilities:
Deposits	111,735,000,000		117,671,000,000		123,227,000,000
Trading liabilities	15,337,000,000		19,820,000,000
Short-term borrowings	21,394,000,000		14,933,000,000
Long-term debt	20,934,000,000		21,745,000,000
Other	5,584,000,000		4,562,000,000
Total liabilities	174,984,000,000	[1]	178,731,000,000	[1]
Parent And Other Subsidiaries Of Common Parent [Member]
Assets:
Cash and due from banks	173,000,000		114,000,000
Interest bearing deposits with banks	923,000,000		714,000,000
Securities purchased under agreements to resell	0		0
Trading assets	18,533,000,000	[2]	21,370,000,000	[2]
Loans	6,967,000,000		4,514,000,000
Other assets	945,000,000		858,000,000
Total assets	27,541,000,000		27,570,000,000
Liabilities:
Deposits	14,333,000,000		13,863,000,000
Trading liabilities	21,374,000,000	[2]	23,910,000,000	[2]
Short-term borrowings	3,513,000,000		2,721,000,000
Long-term debt	3,991,000,000		3,990,000,000
Other	631,000,000		459,000,000
Total liabilities	$ 43,842,000,000		$ 44,943,000,000

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities (“VIEs”) as of June 30, 2013 and 2012 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. Assets: Interest bearing deposits with banks, $221 and $216, Other assets $544 and $533, Total assets $983 and $749 respectively. Liabilities: Long-term debt $92 and $92, Interest, taxes and other liabilities $122 and $152. Total liabilities $614 and $244, respectively.

[2] Trading assets and liabilities exclude the impact of netting which allows the offsetting of amounts relating to certain contracts if certain conditions are met.