Restructuring (Narrative) (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Employee	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 4	$ 7	$ 14	$ 52
Restructuring Reserve	3		3		$ 4
Workforce Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 9
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee			119
Restructuring and Related Cost, Number of Positions Eliminated | Employee			115
Restructuring and Related Cost, Expected Cost	5		$ 5
Payments for Restructuring			8
T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 2
Restructuring and Related Cost, Number of Positions Eliminated | Employee			673
Payments for Restructuring			$ 4
2018 Truck Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			2
Payments for Restructuring			2
International [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2		2		$ 3
International [Member] | Workforce Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			7
Payments for Restructuring			6
International [Member] | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			0
Payments for Restructuring			2
International [Member] | 2018 Truck Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			0
Payments for Restructuring			$ 0