Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income (loss) attributable to Avis Budget Group, Inc. for basic and diluted EPS	$ 674	$ 45	$ 902	$ (594)
Basic weighted average shares outstanding (in shares)	63.7	69.7	67.8	70.8
Non-vested stock (in shares)	0.9	0.5	0.8	0.0
Diluted weighted average shares outstanding (in shares)	64.6	70.2	68.6	70.8
Earnings (loss) per share:
Basic (in dollars per share)	$ 10.58	$ 0.64	$ 13.31	$ (8.40)
Diluted (in dollars per share)	$ 10.45	$ 0.63	$ 13.16	$ (8.40)
Non-vested stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)		0.2	0.4	1.4