Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Additional Information) (Details) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Assets	[1]	$ 863	$ 984
Derivative Asset, Collateral, Obligation to Return Cash, Offset		277	291
Derivative Liabilities	[2]	361	398
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		1,379	1,265
Trading Securities [Member]
Derivative [Line Items]
Derivative Assets		863	984
Trading Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities		$ 361	$ 398

[1] At March 31, 2017, $863 million, net of $277 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2016, $984 million, net of $291 million offsetting cash collateral, is recognized in trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] At March 31, 2017, $361 million, net of $1.4 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2016, $398 million, net of $1.3 billion offsetting cash collateral, is recognized in trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.