Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 6,621		$ 8,656
Derivative Asset, Fair Value, Amount Offset Against Collateral	5,073		6,573
Derivative Assets	1,548	[1]	2,083	[1]
Collateral Held by The Company Against Derivative Asset Positions	68		94
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,480		1,989
Derivative Liability, Fair Value, Gross Liability	5,938		7,514
Derivative Liability, Fair Value, Amount Offset Against Collateral	5,343		7,102
Derivative Liabilities	595	[2]	412	[2]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	575		375
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	6,015		8,041
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,722		6,273
Derivative Assets	1,293		1,768
Collateral Held by The Company Against Derivative Asset Positions	68		94
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,225		1,674
Derivative Liability, Fair Value, Gross Liability	5,350		7,051
Derivative Liability, Fair Value, Amount Offset Against Collateral	4,992		6,802
Derivative Liabilities	358		249
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	20		37
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	338		212
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	23		132
Derivative Asset, Fair Value, Amount Offset Against Collateral	0		0
Derivative Assets	23		132
Collateral Held by The Company Against Derivative Asset Positions	0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	23		132
Derivative Liability, Fair Value, Gross Liability	235		163
Derivative Liability, Fair Value, Amount Offset Against Collateral	0		0
Derivative Liabilities	235		163
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	235		163
Exchange Traded/Cleared [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	583		483
Derivative Asset, Fair Value, Amount Offset Against Collateral	351		300
Derivative Assets	232		183
Collateral Held by The Company Against Derivative Asset Positions	0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	232		183
Derivative Liability, Fair Value, Gross Liability	353		300
Derivative Liability, Fair Value, Amount Offset Against Collateral	351		300
Derivative Liabilities	2		0
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2		0
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	$ 20		$ 37

[1] At June 30, 2013, $1.4 billion, net of $530 million offsetting collateral, is recognized in trading assets and $101 million, net of $151 million offsetting collateral, is recognized in other assets within the Company's Consolidated Balance Sheets. At December 31, 2012, $1.9 billion, net of $730 million offsetting collateral, is recognized in trading assets and $178 million is recognized in other assets within the Company's Consolidated Balance Sheets.

[2] At June 30, 2013, $460 million, net of $1.0 billion offsetting collateral, is recognized in trading liabilities and $135 million is recognized in other liabilities within the Company's Consolidated Balance Sheets. At December 31, 2012, $397 million, net of $1.3 billion offsetting collateral, is recognized in trading liabilities and $15 million is recognized in other liabilities within the Company's Consolidated Balance Sheets.