Derivative Instruments and Other Financial Instruments Used For Hedging (Details 5) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financial Assets
Gross Amounts of Recognized Assets, Derivative assets	$ 1,267	$ 1,085
Gross Amounts Offset in Balance Sheet, Derivative assets	454	493
Net Amounts Presented in Balance Sheet, Derivative assets	813	592
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Derivative assets	50	79
Net Amount, Derivative assets	763	513
Gross Amounts of Recognized Assets, Securities purchased under resale agreements	45	10
Net Amounts Presented in Balance Sheet, Securities purchased under resale agreements	45	10
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities purchased under repurchase agreements	44	10
Net Amount, Securities purchased under repurchase agreements	1
Gross Amounts of Recognized Assets, Financial Assets	1,312	1,095
Gross Amounts Offset in Balance Sheet, Financial Assets	454	493
Net Amounts Presented in Balance Sheet, Financial Assets	858	602
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Financial Assets	94	89
Net Amount, Financial Assets	764	513
Financial Liabilities
Gross Amounts of Recognized Liabilities, Derivative liabilities	1,127	970
Gross Amounts Offset in Balance Sheet, Derivative liabilities	510	423
Net Amounts Presented in Balance Sheet, Derivative liabilities	617	547
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Derivative liabilities	220	144
Net Amount, Derivative liabilities	397	403
Gross Amounts of Recognized Liabilities, Securities sold under repurchase agreements	25	8
Net Amounts Presented in Balance Sheet, Securities sold under repurchase agreements	25	8
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities sold under repurchase agreements	25	8
Gross Amounts of Recognized Liabilities, Financial Liabilities	1,152	978
Gross Amounts Offset in Balance Sheet, Financial Liabilities	510	423
Net Amounts Presented in Balance Sheet, Financial Liabilities	642	555
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Financial Liabilities	245	152
Net Amount, Financial Liabilities	$ 397	$ 403