Goodwill and Intangible Assets (Details 2) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2014
Intangible assets
Intangible assets, gross	$ 5,762	$ 9,717
Amortizable intangible assets, accumulated amortization	(1,575)	(4,684)
Finite-lived Intangible Assets, Accumulated Impairment Losses	(3,103)	(3,103)
Total Intangible Assets- Net	1,084	1,930
Amortizable intangible assets, net	1,084
Amount of fully amortized intangible assets	3,500	703
Divested	478
Divested accumulated amortization	379
Purchases	260	(506)
Amortization of intangible assets	755	852	$ 906
Trilead Ag
Intangible assets
Purchases	11
In-process research and development
Intangible assets
Amortizable intangible assets, gross	0	159
Amortizable intangible assets, net	0	159
Customer contracts, customer lists and distribution agreements
Intangible assets
Amortizable intangible assets, gross	1,394	5,109
Amortizable intangible assets, accumulated amortization	(322)	(3,517)
Finite-lived Intangible Assets, Accumulated Impairment Losses	(856)	(856)
Amortizable intangible assets, net	$ 216	736
Weighted-Average Remaining Useful Lives	5 years
Developed and core technology and patents
Intangible assets
Amortizable intangible assets, gross	$ 4,190	4,218
Amortizable intangible assets, accumulated amortization	(1,232)	(1,110)
Finite-lived Intangible Assets, Accumulated Impairment Losses	(2,138)	(2,138)
Amortizable intangible assets, net	$ 820	970
Weighted-Average Remaining Useful Lives	5 years
Developed and core technology and patents | In-process research and development
Intangible assets
Reclassified	$ 159
Trade name and trade marks
Intangible assets
Amortizable intangible assets, gross	178	231
Amortizable intangible assets, accumulated amortization	(21)	(57)
Finite-lived Intangible Assets, Accumulated Impairment Losses	(109)	(109)
Amortizable intangible assets, net	$ 48	$ 65
Weighted-Average Remaining Useful Lives	7 years