Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Additional Information) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivative [Line Items]
Derivative Assets	$ 1,307	[1]	$ 1,384	[1]
Derivative Liabilities	462	[2]	525	[2]
Trading Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities	462		525
Derivative Liability, Fair Value of Collateral	1,032		(864)
Trading Account Assets [Member]
Derivative [Line Items]
Derivative Assets	1,300		1,400
Derivative Asset, Fair Value of Collateral	$ 449		$ (457)

[1] At December 31, 2014, $1.3 billion, net of $449 million offsetting cash collateral, is recognized in trading assets and derivatives within the Company's Consolidated Balance Sheets. At December 31, 2013, $1.4 billion, net of $457 million offsetting cash collateral, is recognized in trading assets and derivatives within the Company's Consolidated Balance Sheets.

[2] At December 31, 2014, $462 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivatives within the Company's Consolidated Balance Sheets. At December 31, 2013, $525 million, net of $864 million offsetting cash collateral, is recognized in trading liabilities and derivatives within the Company's Consolidated Balance Sheets.