Disclosures About Offsetting Assets and Liabilities - Offsetting Assets (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Offsetting [Abstract]
Derivatives, Gross Amounts of Recognized Assets	$ 87,732	[1]	$ 95,353	[1]
Derivatives, Gross Amounts Offset in the Balance Sheet	77,825	[1],[2]	83,367	[1],[2]
Derivatives, Net Amounts of Assets Presented in the Balance Sheet	9,907	[1]	11,986	[1]
Derivatives, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	853	[1],[3]	627	[1],[3]
Derivatives, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received	0	[1]	0	[1]
Derivatives, Net Amount	9,054	[1]	11,359	[1]
Reverse Repurchase Agreements And Securities Borrowing Fair Value Gross Asset	12,833		5,736
Securities purchased under agreements to resell, Gross Amounts Offset in the Balance Sheet	6,472		2,587
Securities purchased under agreements to resell, Net Amounts of Assets Presented in the Balance Sheet	6,361		3,149
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	6,358	[3]	3,146	[3]
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received	0		0
Securites purchased under agreements to resell, Net Amount	3		3
Total, Gross Amounts of Recognized Assets	100,565		101,089
Total, Gross Amounts Offset in the Balance Sheet	84,297		85,954
Total, Net Amounts of Assets Presented in the Balance Sheet	16,268		15,135
Total, Gross AMounts Not Offset in the Balance Sheet, Financial Instruments	7,211	[3]	3,773	[3]
Total, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received	0		0
Total, Gross Amounts Not Offset in the Balance Sheet, Net Amount	$ 9,057		$ 11,362

[1] The gross amounts of recognized assets includes $86.2 billion of trading related derivatives which are included in trading assets in our consolidated balance sheet and $1.6 billion of derivatives designated in hedging activities that are included in other assets in our consolidated balance sheet at March 31, 2013.The gross amounts of recognized assets includes $93.9 billion of trading related derivatives which are included in trading assets in our consolidated balance sheet and $1.5 billion of derivatives designated in hedging activities that are included in other assets in our consolidated balance sheet at December 31, 2012.

[2] Represents counterparty and cash collateral netting which allow the offsetting of amounts relating to certain contracts if certain conditions are met.

[3] Represents securities received to cover derivative and financing transaction exposures.