Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			$ 17,149
Balance at end of period	$ 16,206		16,206
Net unrealized gains (losses) on available-for-sale securities
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			23
Other comprehensive (loss) income before reclassifications	6	$ 3	0	$ 8
Reclassifications of (gains) losses into earnings	(1)	0	(8)	(3)
Balance at end of period	15		15
Net unrealized gains (losses) on available-for-sale securities | Cumulative Effect, Period of Adoption, Adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			0
Net unrealized gains (losses) on cash flow hedges
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			53
Other comprehensive (loss) income before reclassifications	(430)	57	(91)	201
Reclassifications of (gains) losses into earnings	247	(51)	(15)	(228)
Balance at end of period	(63)		(63)
Net unrealized gains (losses) on cash flow hedges | Cumulative Effect, Period of Adoption, Adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(10)
Unrealized components of defined benefit plans
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(3,366)
Other comprehensive (loss) income before reclassifications			(9)
Reclassifications of (gains) losses into earnings			179
Balance at end of period	(3,196)		(3,196)
Unrealized components of defined benefit plans | Cumulative Effect, Period of Adoption, Adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			0
Cumulative translation adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(437)
Other comprehensive (loss) income before reclassifications			(42)
Reclassifications of (gains) losses into earnings			0
Balance at end of period	(512)		(512)
Cumulative translation adjustment | Cumulative Effect, Period of Adoption, Adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(33)
Accumulated other comprehensive loss
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period	(3,625)	(3,180)	(3,727)	(3,218)
Other comprehensive (loss) income before reclassifications			(142)
Reclassifications of (gains) losses into earnings			156
Balance at end of period	$ (3,756)	$ (3,150)	(3,756)	$ (3,150)
Accumulated other comprehensive loss | Cumulative Effect, Period of Adoption, Adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			$ (43)