Financial Derivatives (Total Gross Derivatives) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Fair Value	$ 6,930	$ 4,941
Derivative Liability, Fair Value	5,235	3,802
Derivative Notional Amount	368,496	347,976
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value	1,663	1,159
Derivative Liability, Fair Value	301	174
Derivative Notional Amount	51,508	52,074
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value	5,267	3,782
Derivative Liability, Fair Value	4,934	3,628
Derivative Notional Amount	$ 316,988	$ 295,902