Derivative Instruments and Other Financial Instruments Used For Hedging (Details 5) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financial Assets
Gross Amounts of Recognized Assets, Derivative assets	$ 2,606	$ 1,828
Gross Amounts Offset in Balance Sheet, Derivative assets	1,170	909
Net Amounts Presented in Balance Sheet, Derivative assets	1,436	919
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Derivative assets	60	60
Net Amount, Derivative assets	1,376	859
Gross Amounts of Recognized Assets, Securities purchased under resale agreements	32	24
Net Amounts Presented in Balance Sheet, Securities purchased under resale agreements	32	24
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities purchased under repurchase agreements	31	24
Net Amount, Securities purchased under repurchase agreements	1	0
Gross Amounts of Recognized Assets, Financial Assets	2,638	1,852
Gross Amounts Offset in Balance Sheet, Financial Assets	1,170	909
Net Amounts Presented in Balance Sheet, Financial Assets	1,468	943
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Financial Assets	91	84
Net Amount, Financial Assets	1,377	859
Financial Liabilities
Gross Amounts of Recognized Liabilities, Derivative liabilities	2,103	1,647
Gross Amounts Offset in Balance Sheet, Derivative liabilities	1,450	872
Net Amounts Presented in Balance Sheet, Derivative liabilities	653	775
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Derivative liabilities	240	180
Derivative, Collateral, Obligation to Return Cash	1	0
Derivative, Collateral, Right to Reclaim Cash	0	0
Net Amount, Derivative liabilities	412	595
Gross Amounts of Recognized Liabilities, Securities sold under repurchase agreements	30	36
Net Amounts Presented in Balance Sheet, Securities sold under repurchase agreements	30	36
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities sold under repurchase agreements	30	36
Gross Amounts of Recognized Liabilities, Financial Liabilities	2,133	1,683
Gross Amounts Offset in Balance Sheet, Financial Liabilities	1,450	872
Net Amounts Presented in Balance Sheet, Financial Liabilities	683	811
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Financial Liabilities	270	216
Net Amount, Financial Liabilities	$ 412	$ 595