Acquisitions (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Goodwill	$ 813	$ 842
Scandinavian Licensee [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Business Acquisition, Date of Acquisition Agreement	Jan. 01, 2015
Business Combination, Consideration Transferred	39
Goodwill	21
Non Cash Charge On Unfavorable License Rights Reacquired With Acquisition With Subsidiaries	22
Budget Licensees [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Business Combination, Consideration Transferred		263
Business Acquisition Purchase Price Allocation Vehicles Net		132
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		58
Goodwill		192
Non Cash Charge On Unfavorable License Rights Reacquired With Acquisition With Subsidiaries		20
Customer Relationships [Member] | Budget Licensees [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Other intangibles, useful life, in years		12 years
Finite-lived Intangible Assets Acquired		10
License Agreements [Member] | Scandinavian Licensee [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Other intangibles, useful life, in years	8 years
Finite-lived Intangible Assets Acquired	31
License Agreements [Member] | Budget Licensees [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Other intangibles, useful life, in years		3 years
Finite-lived Intangible Assets Acquired		$ 48