Restructuring and Impairments - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2012	Apr. 30, 2014	Oct. 31, 2013	Apr. 30, 2012	Jul. 31, 2014	Apr. 30, 2013	Jan. 31, 2013	Jan. 31, 2014	Oct. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 42	$ 25	$ 107
Asset impairment charges	183	97	16
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges				8	11
North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	19
Warrenville [Member] | North America Truck [Member] | Lease Vacancy [Member] [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring charges						16
Warrenville [Member] | North America Truck [Member] | Lease Vacancy Fair Value [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges						19
Warrenville [Member] | North America Truck [Member] | Accrued Rent Expense, Reversal [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring charges						3
Chatham [Member] | North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges							14
Garland Assembly Plant [Member] | North America Truck [Member] | Garland plant closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges								8	12
Huntsville Engine Plant [Member] | North America Truck [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges										1
Huntsville Engine Plant [Member] | North America Truck [Member] | Engine Plant Consolidation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges										2
Indianapolis and Waukesha Foundry [Member] | North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges											13
Asset impairment charges											7
Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges											2
Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Pension And Other Postretirement Contractual Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges											11
Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Restructuring Inventory Adjustments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges											7
Minimum [Member] | Chatham [Member] | North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	0										0
Maximum [Member] | Chatham [Member] | North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	60										60
Maximum [Member] | Indianapolis and Waukesha Foundry [Member] | North America Truck [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	40										40
Discontinuation Engineering Program [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairment charges		19
Discontinued Operations [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairment charges			$ 38