Stockholders' Equity - Components of Accumulated Other Comprehensive Loss, Net of Taxes (Details) $ in Millions	6 Months Ended
	Apr. 30, 2018 USD ($)
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	$ 23,505
Balance at end of period	23,966
Net unrealized gains (losses) on available-for-sale securities
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	29
Other comprehensive income (loss) before reclassifications	1
Reclassifications of (gains) losses into earnings	(9)
Balance at end of period	21
Net unrealized gains (losses) on cash flow hedges
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(48)
Other comprehensive income (loss) before reclassifications	(85)
Reclassifications of (gains) losses into earnings	105
Balance at end of period	(28)
Unrealized components of defined benefit plans
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(2,690)
Other comprehensive income (loss) before reclassifications	1
Reclassifications of (gains) losses into earnings	85
Balance at end of period	(2,604)
Cumulative translation adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(186)
Other comprehensive income (loss) before reclassifications	1
Reclassifications of (gains) losses into earnings	0
Balance at end of period	(371)
Accumulated other comprehensive loss
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(2,895)
Other comprehensive income (loss) before reclassifications	(82)
Reclassifications of (gains) losses into earnings	181
Balance at end of period	(2,982)
Separation and merger transactions | Cumulative translation adjustment
Components of accumulated other comprehensive loss, net of taxes
Adjustments related to transactions	(186)
Separation and merger transactions | Accumulated other comprehensive loss
Components of accumulated other comprehensive loss, net of taxes
Adjustments related to transactions	$ (186)