Restructuring (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring details
Restructuring charges		$ 78	$ 77	$ 38
Asset impairment charges		10
Restructuring reserve
Balance at beginning of period		48	20
Charges incurred		78	77
Cash payments		(53)	(48)
Other		(30)	(1)
Balance at end of period		43	48	20
U.S. car rental
Restructuring details
Restructuring charges		27	23	5
International car rental
Restructuring details
Restructuring charges		19	19	21
Worldwide equipment rental
Restructuring details
Restructuring charges		5	8	9
All Other Operations
Restructuring details
Restructuring charges		0	0	0
Other reconciling items
Restructuring details
Restructuring charges		27	27	3
Direct operating
Restructuring details
Restructuring charges		35	28	23
Selling, general and administrative
Restructuring details
Restructuring charges		43	49	15
Termination benefits
Restructuring details
Restructuring charges		$ 30	42	26
Expected duration for payment of restructuring obligations (in months)		12 months
Restructuring reserve
Balance at beginning of period		$ 20	12
Charges incurred		30	42
Cash payments		(28)	(33)
Other		(1)	(1)
Balance at end of period		21	20	12
Asset writedowns
Restructuring details
Restructuring charges		23	0	0
Facility closure and lease obligation costs
Restructuring details
Restructuring charges		15	15	9
Relocation costs and temporary labor costs
Restructuring details
Restructuring charges		9	19	1
Other
Restructuring details
Restructuring charges		1	1	2
Restructuring reserve
Balance at beginning of period		28	8
Charges incurred		48	35
Cash payments		(25)	(15)
Other		(29)	0
Balance at end of period		$ 22	$ 28	$ 8
Impairment of Former Corporate Headquarters
Restructuring reserve
Other	$ (13)