Fair Value Measurements (Financial Assets Measured At Fair Value On A Recurring and Nonrecurring Basis) (Details) - USD ($) $ in Millions |
Jul. 31, 2021 |
Aug. 01, 2020 |
|---|---|---|
| Marketable equity and debt securities | $ 46 | $ 143 |
| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | ||
| Marketable equity and debt securities | 39 | 32 |
| Significant Observable Inputs (Level 2) [Member] | ||
| Marketable equity and debt securities | 7 | 111 |
| Significant Unobservable Inputs (Level 3) [Member] | ||
| Marketable equity and debt securities | $ 0 | $ 0 |