Guarantor And Non-Guarantor Consolidating Condensed Financial Statements (Consolidating Condensed Statements Of Cash Flows) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 1,524	$ 1,272
Property and equipment additions	(82)	(30)
Proceeds received on asset sales	16	9
Acquisition-related restricted cash		(401)
Other, net	(30)	(11)
Net cash provided by (used in) investing activities exclusive of vehicle programs	(96)	(433)
Decrease (increase) in program cash	(90)	(19)
Investment in vehicles	(8,962)	(6,701)
Proceeds received on disposition of vehicles	6,136	4,379
Investment in debt securities of AESOP-related party		(400)
Proceeds from debt securities of AESOP-related party		400
Net cash used in investing activities of vehicle programs	(2,916)	(2,341)
Net cash provided by (used in) investing activities	(3,012)	(2,774)
Proceeds from long-term borrowings	654
Principal payments on borrowings	(907)	(6)
Net change in short-term borrowings	1
Purchase of warrants	(26)
Proceeds from sale of call options	38
Debt financing fees	(11)	(33)
Other, net	1	1
Net cash provided by (used in) financing activities exclusive of vehicle programs	(250)	(38)
Proceeds from borrowings	9,238	8,235
Principal payments on borrowings	(7,467)	(6,568)
Debt financing fees	(18)	(20)
Net cash provided by financing activities of vehicle programs	1,753	1,647
Net cash provided by (used in) financing activities	1,503	1,609
Effect of changes in exchange rates on cash and cash equivalents	5	(16)
Net (decrease) increase in cash and cash equivalents	20	91
Cash and cash equivalents, beginning of period	534	911
Cash and cash equivalents, end of period	554	1,002
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	(48)	(11)
Acquisition-related restricted cash		(401)
Other, net	4	(7)
Net cash provided by (used in) investing activities exclusive of vehicle programs	4	(408)
Investment in debt securities of AESOP-related party		(400)
Proceeds from debt securities of AESOP-related party		400
Net cash provided by (used in) investing activities	4	(408)
Principal payments on borrowings	(201)
Purchase of warrants	(26)
Proceeds from sale of call options	38
Net intercompany transactions	234	177
Debt financing fees		(14)
Other, net	1	1
Net cash provided by (used in) financing activities exclusive of vehicle programs	46	164
Net cash provided by (used in) financing activities	46	164
Net (decrease) increase in cash and cash equivalents	2	(255)
Cash and cash equivalents, beginning of period	2	257
Cash and cash equivalents, end of period	4	2
Subsidiary Issuers [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	128	183
Property and equipment additions	(19)	(9)
Proceeds received on asset sales	5	6
Other, net	(3)	(3)
Net cash provided by (used in) investing activities exclusive of vehicle programs	(17)	(6)
Investment in vehicles	(2)	(12)
Proceeds received on disposition of vehicles	4	9
Net cash used in investing activities of vehicle programs	2	(3)
Net cash provided by (used in) investing activities	(15)	(9)
Proceeds from long-term borrowings	654
Principal payments on borrowings	(704)	(3)
Net intercompany transactions	(234)	38
Debt financing fees	(11)	(19)
Net cash provided by (used in) financing activities exclusive of vehicle programs	(295)	16
Debt financing fees		(15)
Net cash provided by financing activities of vehicle programs		(15)
Net cash provided by (used in) financing activities	(295)	1
Net (decrease) increase in cash and cash equivalents	(182)	175
Cash and cash equivalents, beginning of period	234	513
Cash and cash equivalents, end of period	52	688
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	42	(256)
Property and equipment additions	(26)	(16)
Proceeds received on asset sales	3	2
Other, net	(1)
Net cash provided by (used in) investing activities exclusive of vehicle programs	(24)	(14)
Investment in vehicles	(19)	(3)
Proceeds received on disposition of vehicles	2	8
Net cash used in investing activities of vehicle programs	(17)	5
Net cash provided by (used in) investing activities	(41)	(9)
Principal payments on borrowings	(2)	(3)
Net intercompany transactions		268
Net cash provided by (used in) financing activities exclusive of vehicle programs	(2)	265
Debt financing fees		(1)
Net cash provided by financing activities of vehicle programs		(1)
Net cash provided by (used in) financing activities	(2)	264
Net (decrease) increase in cash and cash equivalents	(1)	(1)
Cash and cash equivalents, beginning of period	1	3
Cash and cash equivalents, end of period		2
Non-Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	1,402	874
Property and equipment additions	(37)	(5)
Proceeds received on asset sales	8	1
Other, net	(30)	(1)
Net cash provided by (used in) investing activities exclusive of vehicle programs	(59)	(5)
Decrease (increase) in program cash	(90)	(19)
Investment in vehicles	(8,941)	(6,686)
Proceeds received on disposition of vehicles	6,130	4,362
Net cash used in investing activities of vehicle programs	(2,901)	(2,343)
Net cash provided by (used in) investing activities	(2,960)	(2,348)
Net change in short-term borrowings	1
Net intercompany transactions		(1)
Net cash provided by (used in) financing activities exclusive of vehicle programs	1	(1)
Proceeds from borrowings	9,238	8,235
Principal payments on borrowings	(7,467)	(6,568)
Debt financing fees	(18)	(4)
Net cash provided by financing activities of vehicle programs	1,753	1,663
Net cash provided by (used in) financing activities	1,754	1,662
Effect of changes in exchange rates on cash and cash equivalents	5	(16)
Net (decrease) increase in cash and cash equivalents	201	172
Cash and cash equivalents, beginning of period	297	138
Cash and cash equivalents, end of period	498	310
Eliminations [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities		482
Net intercompany transactions		(482)
Net cash provided by (used in) financing activities exclusive of vehicle programs		(482)
Net cash provided by (used in) financing activities		$ (482)