Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			$ 17,149
Balance at end of period	$ 16,258		16,258
Net unrealized gains (losses) on available-for-sale securities
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			23
Effect of change in accounting principle	0
Other comprehensive (loss) income before reclassifications	(8)	$ 3	(6)	$ 5
Reclassifications of (gains) losses into earnings	(4)	0	(7)	(3)
Balance at end of period	10		10
Net unrealized gains (losses) on cash flow hedges
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			53
Effect of change in accounting principle	(10)
Other comprehensive (loss) income before reclassifications	274	111	339	144
Reclassifications of (gains) losses into earnings	(202)	(60)	(262)	(177)
Balance at end of period	120		120
Unrealized components of defined benefit plans
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(3,366)
Effect of change in accounting principle	0
Other comprehensive (loss) income before reclassifications			9
Reclassifications of (gains) losses into earnings			115
Balance at end of period	(3,242)		(3,242)
Cumulative translation adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(437)
Effect of change in accounting principle	(33)
Other comprehensive (loss) income before reclassifications			(43)
Reclassifications of (gains) losses into earnings			0
Balance at end of period	(513)		(513)
Accumulated other comprehensive loss
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(3,700)	(3,294)	(3,727)	(3,218)
Effect of change in accounting principle	(43)
Other comprehensive (loss) income before reclassifications			299
Reclassifications of (gains) losses into earnings			(154)
Balance at end of period	$ (3,625)	$ (3,180)	$ (3,625)	$ (3,180)