Financial Instruments (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions |
Jan. 31, 2016 |
Aug. 02, 2015 |
|---|---|---|
| General Discussion of Derivative Instruments and Hedging Activities [Abstract] | ||
| Derivative Asset, Fair Value, Gross Asset | $ 66 | $ 54 |
| Derivative Asset, Not Offset, Policy Election Deduction | (31) | (13) |
| Derivative Asset, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election | 35 | 41 |
| Derivative Liability, Fair Value, Gross Liability | 39 | 20 |
| Derivative Liability, Not Offset, Policy Election Deduction | (31) | (13) |
| Derivative Liability, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election | $ 8 | $ 7 |