Stockholders' Deficit - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Jan. 31, 2020	Apr. 30, 2021	Apr. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss, beginning balance	$ (1,786)	$ (2,084)	$ (1,912)	$ (1,865)	$ (1,912)
Other comprehensive income before reclassifications	11	(103)		73	(111)
Amounts reclassified out of accumulated other comprehensive loss	17	24		34	49
Net current-period other comprehensive income (loss)	28	(79)		107	(62)
Reclassification of stranded tax effects			0		(189)
Accumulated other comprehensive loss, ending balance	(1,758)	(2,163)	(2,084)	(1,758)	(2,163)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss, beginning balance	(379)	(329)	(321)	(404)	(321)
Other comprehensive income before reclassifications	11	(103)		36	(111)
Amounts reclassified out of accumulated other comprehensive loss	0	0		0	0
Net current-period other comprehensive income (loss)	11	(103)		36	(111)
Reclassification of stranded tax effects					0
Accumulated other comprehensive loss, ending balance	(368)	(432)	(329)	(368)	(432)
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss, beginning balance	(1,407)	(1,755)	(1,591)	(1,461)	(1,591)
Other comprehensive income before reclassifications	0	0		37	0
Amounts reclassified out of accumulated other comprehensive loss	17	24		34	49
Net current-period other comprehensive income (loss)	17	24		71	49
Reclassification of stranded tax effects					(189)
Accumulated other comprehensive loss, ending balance	$ (1,390)	$ (1,731)	(1,755)	$ (1,390)	(1,731)
Accumulated Deficit
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification of stranded tax effects			$ 189		$ 189