Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 4,465	$ 5,839
Derivative Asset, Fair Value, Amount Offset Against Collateral		3,313	4,532
Derivative Assets	[1]	1,152	1,307
Collateral Held by The Company Against Derivative Asset Positions		66	63
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1,086	1,244
Derivative Liability, Fair Value, Gross Liability		4,428	5,577
Derivative Liability, Fair Value, Amount Offset Against Collateral		3,964	5,115
Derivative Liabilities	[2]	464	462
Derivative, Collateral, Right to Reclaim Securities		19	12
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		445	450
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		4,184	5,127
Derivative Asset, Fair Value, Amount Offset Against Collateral		3,156	4,095
Derivative Assets		1,028	1,032
Collateral Held by The Company Against Derivative Asset Positions		66	63
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		962	969
Derivative Liability, Fair Value, Gross Liability		4,162	5,001
Derivative Liability, Fair Value, Amount Offset Against Collateral		3,807	4,678
Derivative Liabilities		355	323
Derivative, Collateral, Right to Reclaim Securities		19	12
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		336	311
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		21	25
Derivative Asset, Fair Value, Amount Offset Against Collateral		0	0
Derivative Assets		21	25
Collateral Held by The Company Against Derivative Asset Positions		0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		21	25
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		105	133
Derivative Liability, Fair Value, Amount Offset Against Collateral		0	0
Derivative Liabilities		105	133
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		105	133
Exchange Traded [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		260	687
Derivative Asset, Fair Value, Amount Offset Against Collateral		157	437
Derivative Assets		103	250
Collateral Held by The Company Against Derivative Asset Positions		0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		103	250
Derivative Liability, Fair Value, Gross Liability		161	443
Derivative Liability, Fair Value, Amount Offset Against Collateral		157	437
Derivative Liabilities		4	6
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ 4	$ 6

[1] 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. 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 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. 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.