Restructuring - Additional Information (Detail) $ in Millions	12 Months Ended				36 Months Ended	48 Months Ended
	Dec. 31, 2017 USD ($) Employee	Dec. 31, 2016 USD ($) Employee	Dec. 31, 2015 USD ($) Employee	Dec. 31, 2014 Employee	Dec. 31, 2017 USD ($) Employee	Dec. 31, 2017 USD ($) Employee
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 63	$ 29	$ 18
2018 Truck Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 5
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee	25
Restructuring and Related Cost, Number of Positions Eliminated | Employee	20
Restructuring and Related Cost, Expected Cost	$ 3				$ 3	$ 3
2015 Acquisition Integration [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 9	$ 9
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee		115	180
Restructuring and Related Cost, Number of Positions Eliminated | Employee					260
T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 35
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee	680
Restructuring and Related Cost, Number of Positions Eliminated | Employee	665
2014 T15 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 21	$ 9
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee		615	325
Restructuring and Related Cost, Number of Positions Eliminated | Employee						990
2011 Avis Europe Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ (1)
Restructuring and Related Cost, Expected Number of Positions Eliminated | Employee				230
Americas | 2018 Truck Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 5
Americas | 2015 Acquisition Integration [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0	$ 1
Americas | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	25
Americas | 2014 T15 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		11	6
Americas | 2011 Avis Europe Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0
International | 2018 Truck Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0
International | 2015 Acquisition Integration [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		9	8
International | T17 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 10
International | 2014 T15 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		10	$ 3
International | 2011 Avis Europe Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ (1)