Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Additional Information) (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative Assets	[1]	$ 1,449	$ 1,307
Derivative Asset, Collateral, Obligation to Return Cash, Offset		541	449
Derivative Liabilities	[2]	565	462
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,097	1,032
Trading Securities [Member]
Derivative [Line Items]
Derivative Assets		1,449	1,307
Trading Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities		$ 565	$ 462

[1] At September 30, 2015, $1.4 billion, net of $541 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2014, $1.3 billion, net of $449 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] At September 30, 2015, $565 million, net of $1.1 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2014, $462 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.