Guarantor And Non-Guarantor Consolidating Condensed Financial Statements (Consolidating Condensed Statements Of Cash Flows) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 300	$ 253
Property and equipment additions	(21)	(20)
Proceeds received on asset sales	4	3
Payments to Acquire Businesses, Net of Cash Acquired	(476)
Other, net	26	(1)
Net cash used in investing activities exclusive of vehicle programs	(467)	(18)
Decrease (increase) in program cash	(24)	(39)
Investment in vehicles	(3,111)	(3,053)
Proceeds received on disposition of vehicles	2,394	2,143
Net cash used in investing activities of vehicle programs	(741)	(949)
Net cash provided by (used in) investing activities	(1,208)	(967)
Proceeds from long-term borrowings	1,225	624
Principal payments on borrowings	(788)	(520)
Net change in short-term borrowings	(31)	(12)
Purchase of warrants	(28)	(13)
Proceeds from sale of call options	37	19
Debt financing fees	(10)	(8)
Other, net	2	0
Net cash provided by financing activities exclusive of vehicle programs	407	90
Proceeds from borrowings	3,762	3,140
Principal payments on borrowings	(3,279)	(2,440)
Debt financing fees	(17)	(7)
Net cash provided by financing activities of vehicle programs	466	693
Net cash provided by (used in) financing activities	873	783
Effect of changes in exchange rates on cash and cash equivalents	(2)	3
Net (decrease) increase in cash and cash equivalents	(37)	72
Cash and cash equivalents, beginning of period	606	534
Cash and cash equivalents, end of period	569	606
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	6	(6)
Other, net		4
Net cash used in investing activities exclusive of vehicle programs		4
Net cash provided by (used in) investing activities		4
Principal payments on borrowings	(89)	(101)
Purchase of warrants	(28)	(13)
Proceeds from sale of call options	37	19
Net intercompany transactions	73	100
Other, net	2
Net cash provided by financing activities exclusive of vehicle programs	(5)	5
Net cash provided by (used in) financing activities	(5)	5
Net (decrease) increase in cash and cash equivalents	1	3
Cash and cash equivalents, beginning of period	5	2
Cash and cash equivalents, end of period	6	5
Subsidiary Issuers [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	(12)	(86)
Property and equipment additions	(5)	(5)
Proceeds received on asset sales	2	2
Payments to Acquire Businesses, Net of Cash Acquired	(513)
Other, net	(1)	(1)
Net cash used in investing activities exclusive of vehicle programs	(517)	(4)
Investment in vehicles	(1)	(1)
Proceeds received on disposition of vehicles	1	4
Net cash used in investing activities of vehicle programs		3
Net cash provided by (used in) investing activities	(517)	(1)
Proceeds from long-term borrowings	1,225	624
Principal payments on borrowings	(698)	(419)
Net intercompany transactions	(73)	(99)
Debt financing fees	(10)	(8)
Net cash provided by financing activities exclusive of vehicle programs	444	98
Net cash provided by (used in) financing activities	444	98
Net (decrease) increase in cash and cash equivalents	(85)	11
Cash and cash equivalents, beginning of period	102	234
Cash and cash equivalents, end of period	17	245
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	(25)	8
Property and equipment additions	(10)	(7)
Payments to Acquire Businesses, Net of Cash Acquired	16
Other, net	28
Net cash used in investing activities exclusive of vehicle programs	34	(7)
Net cash provided by (used in) investing activities	34	(7)
Principal payments on borrowings	(1)	(1)
Net intercompany transactions		1
Net cash provided by financing activities exclusive of vehicle programs	(1)
Net cash provided by (used in) financing activities	(1)
Net (decrease) increase in cash and cash equivalents	8	1
Cash and cash equivalents, beginning of period		1
Cash and cash equivalents, end of period	8	2
Non-Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	331	334
Property and equipment additions	(6)	(8)
Proceeds received on asset sales	2	1
Payments to Acquire Businesses, Net of Cash Acquired	21
Other, net	(1)	(4)
Net cash used in investing activities exclusive of vehicle programs	16	(11)
Decrease (increase) in program cash	(24)	(39)
Investment in vehicles	(3,110)	(3,052)
Proceeds received on disposition of vehicles	2,393	2,139
Net cash used in investing activities of vehicle programs	(741)	(952)
Net cash provided by (used in) investing activities	(725)	(963)
Principal payments on borrowings		1
Net change in short-term borrowings	(31)	(12)
Net intercompany transactions		1
Net cash provided by financing activities exclusive of vehicle programs	(31)	(10)
Proceeds from borrowings	3,762	3,140
Principal payments on borrowings	(3,279)	(2,440)
Debt financing fees	(17)	(7)
Net cash provided by financing activities of vehicle programs	466	693
Net cash provided by (used in) financing activities	435	683
Effect of changes in exchange rates on cash and cash equivalents	(2)	3
Net (decrease) increase in cash and cash equivalents	39	57
Cash and cash equivalents, beginning of period	499	297
Cash and cash equivalents, end of period	538	354
Eliminations [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities		3
Payments to Acquire Businesses, Net of Cash Acquired	0
Net intercompany transactions		(3)
Net cash provided by financing activities exclusive of vehicle programs		(3)
Net cash provided by (used in) financing activities		(3)
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 0