Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Assets	[1]	$ 1,735	$ 1,152
Collateral Held by The Company Against Derivative Asset Positions		103	66
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1,632	1,086
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		5,826	4,465
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		4,091	3,313
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		4,757	3,964
Derivative Liabilities	[2]	654	464
Derivative, Collateral, Right to Reclaim Securities		26	19
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		628	445
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		5,411	4,428
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		5,506	4,184
Derivative Assets		1,563	1,028
Collateral Held by The Company Against Derivative Asset Positions		103	66
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1,460	962
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		3,943	3,156
Derivative Liability, Fair Value, Gross Liability		5,169	4,162
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		4,609	3,807
Derivative Liabilities		560	355
Derivative, Collateral, Right to Reclaim Securities		26	19
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		534	336
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		36	21
Derivative Assets		36	21
Collateral Held by The Company Against Derivative Asset Positions		0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		36	21
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		0	0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		0	0
Derivative Liability, Not Subject to Master Netting Arrangement		93	105
Derivative Liabilities		93	105
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		93	105
Exchange Traded [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		284	260
Derivative Assets		136	103
Collateral Held by The Company Against Derivative Asset Positions		0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		136	103
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		148	157
Derivative Liability, Fair Value, Gross Liability		149	161
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		148	157
Derivative Liabilities		1	4
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ 1	$ 4

[1] At March 31, 2016, $1.7 billion, net of $607 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 March 31, 2016, $654 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.