Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Additional Information) (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Assets	[1]	$ 1,669	$ 1,152
Derivative Asset, Collateral, Obligation to Return Cash, Offset		786	397
Derivative Liabilities	[2]	458	464
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,290	1,048
Trading Securities [Member]
Derivative [Line Items]
Derivative Assets		1,700	1,200
Trading Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities		$ 458	$ 464

[1] At June 30, 2016, $1.7 billion, net of $786 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2015, $1.2 billion, net of $397 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] At June 30, 2016, $458 million, net of $1.3 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2015, $464 million, net of $1.0 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.