Quarterly Financial Information (Unaudited) (Statement of Operations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended			48 Months Ended	60 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2013
Revenues:
Worldwide car rental	$ 2,000	$ 2,563	$ 2,304	$ 2,039	$ 2,019	$ 2,538	$ 2,197	$ 1,955	$ 4,343	$ 4,153	$ 6,907	$ 6,690	$ 8,907	$ 8,709	$ 7,153
Worldwide equipment rental	416	413	384	358	401	403	381	353	743	734	1,155	1,138	1,571	1,539	1,382
All other operations	143	145	142	139	135	134	130	129	280	258	425	392	568	527	478
Total revenues	2,559	3,121	2,830	2,536	2,555	3,075	2,708	2,437	5,366	5,145	8,487	8,220	11,046	10,775	9,013
Expenses:
Direct operating	1,575	1,702	1,594	1,443	1,449	1,547	1,417	1,364	3,037	2,781	4,738	4,328	6,314	5,777	4,861
Depreciation of revenue earning equipment and lease charges, net	853	746	708	726	641	672	632	589	1,434	1,220	2,180	1,893	3,034	2,533	2,128
Selling, general and administrative	245	303	264	276	234	282	287	250	541	537	845	819	1,088	1,053	978
Interest expense, net	164	164	164	156	171	179	182	175	320	357	484	536	648	707	647
Other (income) expense, net	6	3	(21)	(3)	21	83	(2)	0	(24)	(2)	(21)	81	(15)	102	34
Total expenses	2,843	2,918	2,709	2,598	2,516	2,763	2,516	2,378	5,308	4,893	8,226	7,657	11,069	10,172	8,648
Income (loss) before income taxes	(284)	203	121	(62)	39	312	192	59	58	252	261	563	(23)	603	365
Provision for taxes on income (loss)	50	(54)	(49)	(7)	(57)	(110)	(81)	(53)	(56)	(135)	(109)	(243)	(59)	(301)	(181)
Net income (loss)	$ (234)	$ 149	$ 72	$ (69)	$ (18)	$ 202	$ 111	$ 6	$ 2	$ 117	$ 152	$ 320	$ (82)	$ 302	$ 184
Weighted average shares outstanding:
Basic (in shares)	459	459	452	447	447	425	401	416	450	408	453	414	454	422	420
Diluted (in shares)	465	464	465	447	447	465	465	461	457	463	465	464	454	464	448
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.51)	$ 0.32	$ 0.16	$ (0.15)	$ (0.04)	$ 0.48	$ 0.28	$ 0.01	$ 0.00	$ 0.29	$ 0.34	$ 0.77	$ (0.18)	$ 0.72	$ 0.44
Diluted (in dollars per share)	$ (0.50)	$ 0.32	$ 0.15	$ (0.15)	$ (0.04)	$ 0.44	$ 0.25	$ 0.02	$ 0.00	$ 0.26	$ 0.33	$ 0.70	$ (0.18)	$ 0.67	$ 0.41
Interest on Convertible Senior Notes, net of tax						$ 2	$ 4	$ 1		$ 5	$ 1	$ 7	$ 0	$ 8	$ 0
As Previously Reported
Revenues:
Worldwide car rental					$ 2,020	2,534	2,195	1,957		4,152		6,686
Worldwide equipment rental					401	402	384	351		735		1,137
All other operations					135	134	136	128		264		397
Total revenues					2,556	3,070	2,715	2,436		5,151		8,220
Expenses:
Direct operating					1,439	1,525	1,406	1,351		2,757		4,283
Depreciation of revenue earning equipment and lease charges, net					643	677	641	587		1,228		1,905
Selling, general and administrative					222	278	275	252		527		803
Interest expense, net					169	179	182	175		357		535
Other (income) expense, net					21	83	(1)	(1)		(2)		82
Total expenses					2,494	2,742	2,503	2,364		4,867		7,608
Income (loss) before income taxes					62	328	212	72		284		612
Provision for taxes on income (loss)					(63)	(113)	(91)	(54)		(145)		(258)
Net income (loss)					$ (1)	$ 215	$ 121	$ 18		$ 139		$ 354
Weighted average shares outstanding:
Basic (in shares)					447	425	401	416		408		414
Diluted (in shares)					464	465	465	461		463		464
Earnings (loss) per share:
Basic (in dollars per share)					$ 0.00	$ 0.51	$ 0.30	$ 0.04		$ 0.34		$ 0.86
Diluted (in dollars per share)					$ 0.00	$ 0.47	$ 0.27	$ 0.04		$ 0.31		$ 0.78
Revision Adjustment
Revenues:
Worldwide car rental					$ 0	$ 0	$ 0	$ 0		$ 0		$ 0
Worldwide equipment rental					0	0	0	0		0		0
All other operations					0	0	(6)	1		(5)		(5)
Total revenues					0	0	(6)	1		(5)		(5)
Expenses:
Direct operating					0	15	8	7		16		30
Depreciation of revenue earning equipment and lease charges, net					0	(2)	(13)	(7)		(20)		(23)
Selling, general and administrative					0	(6)	5	(4)		1		(3)
Interest expense, net					0	0	0	0		0		0
Other (income) expense, net					0	0	0	3		2		2
Total expenses					0	7	0	(1)		(1)		6
Income (loss) before income taxes					0	(7)	(6)	2		(4)		(11)
Provision for taxes on income (loss)					0	2	6	(4)		2		4
Net income (loss)					0	(5)	0	(2)		(2)		(7)
As Revised
Revenues:
Worldwide car rental					2,020	2,534	2,195	1,957		4,152		6,686		8,707	7,162
Worldwide equipment rental					401	402	384	351		735		1,137		1,538	1,385
All other operations					135	134	130	129		259		392		527	478
Total revenues					2,556	3,070	2,709	2,437		5,146		8,215		10,772	9,025
Expenses:
Direct operating					1,439	1,540	1,414	1,358		2,773		4,313		5,752	4,806
Depreciation of revenue earning equipment and lease charges, net					643	675	628	580		1,208		1,882		2,526	2,129
Selling, general and administrative					222	272	280	248		528		800		1,022	968
Interest expense, net					169	179	182	175		357		535		704	645
Other (income) expense, net					21	83	(1)	2		0		84		105	36
Total expenses					2,494	2,749	2,503	2,363		4,866		7,614		10,109	8,584
Income (loss) before income taxes					62	321	206	74		280		601		663	441
Provision for taxes on income (loss)					(63)	(111)	(85)	(58)		(143)		(254)		(317)	(202)
Net income (loss)					$ (1)	$ 210	$ 121	$ 16		$ 137		$ 347		$ 346	$ 239
Weighted average shares outstanding:
Basic (in shares)					447	425	401	416		408		414		422	420
Diluted (in shares)					464	465	465	461		463		464		464	448
Earnings (loss) per share:
Basic (in dollars per share)					$ 0.00	$ 0.49	$ 0.30	$ 0.04		$ 0.33		$ 0.84		$ 0.82	$ 0.57
Diluted (in dollars per share)					$ 0.00	$ 0.46	$ 0.27	$ 0.04		$ 0.31		$ 0.76		$ 0.76	$ 0.53
Restatement Adjustment
Revenues:
Worldwide car rental					$ (1)	$ 4	$ 2	$ (2)		$ 1		$ 4		$ 2	$ (9)
Worldwide equipment rental					0	1	(3)	2		(1)		1		1	(3)
All other operations					0	0	0	0		(1)		0		0	0
Total revenues					(1)	5	(1)	0		(1)		5		3	(12)
Expenses:
Direct operating					10	7	3	6		8		15		25	55
Depreciation of revenue earning equipment and lease charges, net					(2)	(3)	4	9		12		11		7	(1)
Selling, general and administrative					12	10	7	2		9		19		31	10
Interest expense, net					2	0	0	0		0		1		3	2
Other (income) expense, net					0	0	(1)	(2)		(2)		(3)		(3)	(2)
Total expenses					22	14	13	15		27		43		63	64
Income (loss) before income taxes					(23)	(9)	(14)	(15)		(28)		(38)		(60)	(76)	$ 35	$ 46
Provision for taxes on income (loss)					6	1	4	5		8		11		16	21
Net income (loss)					$ (17)	$ (8)	$ (10)	$ (10)		$ (20)		$ (27)		$ (44)	$ (55)	$ 21