Stockholders' Equity - Components of AOCI (Details) - USD ($) shares in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016	May 24, 2016	Oct. 13, 2015
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			$ 31,518,000,000
Balance at end of period	$ 29,047,000,000		$ 29,047,000,000
Share Repurchase program
Stock Repurchase Program
Stock repurchase program authorized amount					$ 3,000,000,000.0	$ 3,000,000,000.0
Common stock retired (in shares)			2.1
Repurchases of common stock recorded as a reduction to stockholders' equity			$ 39,000,000
Share repurchase authorization remaining	2,000,000,000		$ 2,000,000,000
ASR Agreement
Stock Repurchase Program
Common stock retired (in shares)			59.0
Repurchases of common stock recorded as a reduction to stockholders' equity			$ 1,300,000,000
Change in net unrealized (losses) gains on available-for-sale securities:
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			54,000,000
Transfer related to the Everett Transaction			(9,000,000)
Other comprehensive (loss) income before reclassifications	(4,000,000)	$ 0	(18,000,000)	$ 3,000,000
Reclassifications of (gains) loss into earnings	0	(4,000,000)	0	2,000,000
Balance at end of period	27,000,000		27,000,000
Change in net unrealized losses on cash flow hedges:
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			35,000,000
Transfer related to the Everett Transaction			0
Other comprehensive (loss) income before reclassifications	8,000,000	$ (160,000,000)	113,000,000	$ (33,000,000)
Reclassifications of (gains) loss into earnings			(201,000,000)
Balance at end of period	(53,000,000)		(53,000,000)
Unrealized components of defined benefit plans
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(5,642,000,000)
Transfer related to the Everett Transaction			1,820,000,000
Other comprehensive (loss) income before reclassifications			465,000,000
Reclassifications of (gains) loss into earnings			152,000,000
Balance at end of period	(3,205,000,000)		(3,205,000,000)
Change in cumulative translation adjustment
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(1,046,000,000)
Transfer related to the Everett Transaction			768,000,000
Other comprehensive (loss) income before reclassifications			(35,000,000)
Reclassifications of (gains) loss into earnings			0
Balance at end of period	(313,000,000)		(313,000,000)
Accumulated other comprehensive loss
Components of accumulated other comprehensive loss, net of taxes
Balance at beginning of period			(6,599,000,000)
Transfer related to the Everett Transaction			2,579,000,000
Other comprehensive (loss) income before reclassifications			525,000,000
Reclassifications of (gains) loss into earnings			(49,000,000)
Balance at end of period	$ (3,544,000,000)		$ (3,544,000,000)