Derivative Instruments and Other Financial Instruments Used For Hedging (Details 5) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Financial Assets
Gross Amounts of Recognized Assets, Derivative assets	$ 2,071	$ 1,799
Gross Amounts Offset in Balance Sheet, Derivative assets	948	887
Net Amounts Presented in Balance Sheet, Derivative assets	1,123	912
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Derivative assets	67	113
Net Amount, Derivative assets	1,056	799
Gross Amounts of Recognized Assets, Securities purchased under resale agreements	82	62
Net Amounts Presented in Balance Sheet, Securities purchased under resale agreements	82	62
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities purchased under repurchase agreements	81	61
Net Amount, Securities purchased under repurchase agreements	1	1
Gross Amounts of Recognized Assets, Financial Assets	2,153	1,861
Gross Amounts Offset in Balance Sheet, Financial Assets	948	887
Net Amounts Presented in Balance Sheet, Financial Assets	1,205	974
Gross Amounts Not Offset In Balance Sheet, Financial Instruments, Financial Assets	148	174
Net Amount, Financial Assets	1,057	800
Financial Liabilities
Gross Amounts of Recognized Liabilities, Derivative liabilities	1,770	1,624
Gross Amounts Offset in Balance Sheet, Derivative liabilities	958	787
Net Amounts Presented in Balance Sheet, Derivative liabilities	812	837
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Derivative liabilities	237	162
Net Amount, Derivative liabilities	575	675
Gross Amounts of Recognized Liabilities, Securities sold under repurchase agreements	35	68
Net Amounts Presented in Balance Sheet, Securities sold under repurchase agreements	35	68
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Securities sold under repurchase agreements	35	68
Gross Amounts of Recognized Liabilities, Financial Liabilities	1,805	1,692
Gross Amounts Offset in Balance Sheet, Financial Liabilities	958	787
Net Amounts Presented in Balance Sheet, Financial Liabilities	847	905
Gross Amount Not Offset in Balance Sheet, Financial Instruments, Financial Liabilities	272	230
Net Amount, Financial Liabilities	$ 575	$ 675