Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended				12 Months Ended
	Nov. 30, 2017	Dec. 31, 2016	Apr. 30, 2015	Aug. 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Commitments and Contingencies
Impairment					23	21	$ 68
Goodwill		$ 1,007			1,073	$ 1,007	$ 973
2017 Avis and Budget Licensees [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred					9
Business Combination, Consideration Transferred, Other					$ 4
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					3 years
Impairment					$ 2
2017 Avis and Budget Licensees [Member] | Licensing Agreements [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired					12
ACL Hire Limited [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Nov. 01, 2017
Business Combination, Consideration Transferred					5
Commitments and Contingencies					2
Goodwill					$ 5
Maggiore Group [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Apr. 01, 2015
Business Combination, Consideration Transferred			$ 160
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							10 years
Goodwill							$ 82
Maggiore Group [Member] | Other Intangible Assets [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired							34
Maggiore Group [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired							50
Maggiore Group [Member] | Licensing Agreements [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired							11
Brazil [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Apr. 01, 2015	Aug. 01, 2013
Goodwill							77
Equity Method Investment, Ownership Percentage			50.00%	50.00%
Payments to Acquire Equity Method Investments							8
Due to Related Parties							46
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Loss							8
France Cars [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition		Dec. 01, 2016
Business Combination, Consideration Transferred		$ 45
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						8 years
Goodwill		$ 22				$ 22
France Cars [Member] | Other Intangible Assets [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired						9
France Cars [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired						$ 6
Avis and Budget Licensees [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred							62
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities							$ 23
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							8 years
Goodwill							$ 29
Non Cash Charge On Unfavorable License Rights Reacquired With Acquisition With Subsidiaries							25
Avis and Budget Licensees [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired							12
Avis and Budget Licensees [Member] | Licensing Agreements [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired							$ 36