Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 6,067		$ 5,839
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,592		4,532
Derivative Assets	1,475	[1]	1,307	[1]
Collateral Held by The Company Against Derivative Asset Positions	72		63
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,403		1,244
Derivative Liability, Fair Value, Gross Liability	5,728		5,577
Derivative Liability, Fair Value, Amount Offset Against Collateral	5,176		5,115
Derivative Liabilities	552	[2]	462	[2]
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	27		12
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	525		450
Trading Securities [Member]
Derivative [Line Items]
Derivative Assets	1,500		1,300
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	5,408		5,127
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,172		4,095
Derivative Assets	1,236		1,032
Collateral Held by The Company Against Derivative Asset Positions	72		63
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1,164		969
Derivative Liability, Fair Value, Gross Liability	5,185		5,001
Derivative Liability, Fair Value, Amount Offset Against Collateral	4,756		4,678
Derivative Liabilities	429		323
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	27		12
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	402		311
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	45		25
Derivative Asset, Fair Value, Amount Offset Against Collateral	0		0
Derivative Assets	45		25
Collateral Held by The Company Against Derivative Asset Positions	0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	45		25
Derivative Liability, Fair Value, Gross Liability	119		133
Derivative Liability, Fair Value, Amount Offset Against Collateral	0		0
Derivative Liabilities	119		133
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	119		133
Exchange Traded [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	614		687
Derivative Asset, Fair Value, Amount Offset Against Collateral	420		437
Derivative Assets	194		250
Collateral Held by The Company Against Derivative Asset Positions	0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	194		250
Derivative Liability, Fair Value, Gross Liability	424		443
Derivative Liability, Fair Value, Amount Offset Against Collateral	420		437
Derivative Liabilities	4		6
Financial Instruments, Owned and Pledged as Collateral, at Fair Value	0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 4		$ 6

[1] At March 31, 2015, $1.5 billion, net of $530 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 March 31, 2015, $552 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.