Postretirement Benefits - Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2015	Oct. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liability	$ (2,995)	$ (2,862)
Net liability recognized	(3,088)	(2,955)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	13	0
Current liability	(15)	(15)
Noncurrent liability	(1,555)	(1,399)
Net liability recognized	(1,557)	(1,414)
Net actuarial loss	(2,234)	(2,019)
Net prior service cost (benefit)	0	1
Net amount recognized	2,234	2,020
Amortization of prior service cost (benefit)	0
Amortization of cumulative losses	103
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Noncurrent asset	0	0
Current liability	(78)	(79)
Noncurrent liability	(1,440)	(1,463)
Net liability recognized	(1,518)	(1,542)
Net actuarial loss	(618)	(664)
Net prior service cost (benefit)	(1)	(6)
Net amount recognized	617	$ 658
Amortization of prior service cost (benefit)	(1)
Amortization of cumulative losses	$ 33