Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions |
Apr. 30, 2018 |
Oct. 31, 2017 |
|---|---|---|
| Statement of Financial Position [Abstract] | ||
| Allowance for doubtful accounts | $ 39 | $ 42 |
| Preferred stock, par value (in dollars per share) | $ 0.01 | $ 0.01 |
| Preferred stock, shares authorized | 300,000,000 | 300,000,000 |
| Preferred stock, shares issued | 0 | 0 |
| Preferred stock, shares outstanding | 0 | 0 |
| Common stock, par value (in dollars per share) | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 9,600,000,000 | 9,600,000,000 |
| Common stock, shares issued | 1,527,000,000 | 1,595,000,000 |
| Common stock, shares outstanding | 1,527,000,000 | 1,595,000,000 |