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, 2015	Mar. 31, 2014
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 503	$ 390
Property and equipment additions	(41)	(36)
Proceeds received on asset sales	3	3
Payments to Acquire Restricted Investments	(36)	(124)
Other, net	0	(7)
Net cash used in investing activities exclusive of vehicle programs	(74)	(164)
Decrease (increase) in program cash	51	12
Investment in vehicles	(3,195)	(3,275)
Proceeds received on disposition of vehicles	2,444	2,470
Net cash used in investing activities of vehicle programs	(700)	(793)
Net cash used in investing activities	(774)	(957)
Proceeds from long-term borrowings	376	295
Principal payments on borrowings	(6)	(5)
Net change in short-term borrowings	(7)	11
Repurchases of common stock	(33)	(67)
Debt financing fees	(6)	(5)
Other, net	0	(1)
Net cash provided by financing activities exclusive of vehicle programs	324	228
Proceeds from borrowings	3,667	3,775
Principal payments on borrowings	(3,458)	(3,280)
Debt financing fees	(6)	(7)
Net cash provided by financing activities of vehicle programs	203	488
Net cash provided by financing activities	527	716
Effect of changes in exchange rates on cash and cash equivalents	(26)	(1)
Net increase in cash and cash equivalents	230	148
Cash and cash equivalents, beginning of period	624	693
Cash and cash equivalents, end of period	854	841
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	0	2
Property and equipment additions	0	0
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Other, net	33	57
Net cash used in investing activities exclusive of vehicle programs	33	57
Decrease (increase) in program cash	0	0
Investment in vehicles	0	0
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	0	0
Net cash used in investing activities	33	57
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Repurchases of common stock	(33)	(67)
Debt financing fees	0	0
Other, net	0	(1)
Net cash provided by financing activities exclusive of vehicle programs	(33)	(68)
Proceeds from borrowings	0	0
Principal payments on borrowings	0	0
Debt financing fees	0	0
Net cash provided by financing activities of vehicle programs	0	0
Net cash provided by financing activities	(33)	(68)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	0	(9)
Cash and cash equivalents, beginning of period	2	14
Cash and cash equivalents, end of period	2	5
Subsidiary Issuers [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	12	284
Property and equipment additions	(4)	(3)
Proceeds received on asset sales	1	2
Payments to Acquire Restricted Investments	0	0
Other, net	0	(7)
Net cash used in investing activities exclusive of vehicle programs	(3)	(8)
Decrease (increase) in program cash	0	0
Investment in vehicles	(3)	(1)
Proceeds received on disposition of vehicles	4	3
Net cash used in investing activities of vehicle programs	1	2
Net cash used in investing activities	(2)	(6)
Proceeds from long-term borrowings	375	0
Principal payments on borrowings	(4)	(4)
Net change in short-term borrowings	0	0
Repurchases of common stock	0	0
Debt financing fees	(6)	0
Other, net	(33)	(57)
Net cash provided by financing activities exclusive of vehicle programs	332	(61)
Proceeds from borrowings	0	0
Principal payments on borrowings	0	0
Debt financing fees	0	0
Net cash provided by financing activities of vehicle programs	0	0
Net cash provided by financing activities	332	(61)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	342	217
Cash and cash equivalents, beginning of period	210	242
Cash and cash equivalents, end of period	552	459
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	45	14
Property and equipment additions	(19)	(17)
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Intercompany loan advances	(24)
Other, net	1	0
Net cash used in investing activities exclusive of vehicle programs	(42)	(17)
Decrease (increase) in program cash	0	0
Investment in vehicles	0	(8)
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	0	(8)
Net cash used in investing activities	(42)	(25)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	(1)	(1)
Net change in short-term borrowings	0	0
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	0	0
Net cash provided by financing activities exclusive of vehicle programs	(1)	(1)
Proceeds from borrowings	0	0
Principal payments on borrowings	(2)	0
Debt financing fees	0	0
Net cash provided by financing activities of vehicle programs	(2)	0
Net cash provided by financing activities	(3)	(1)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	0	(12)
Cash and cash equivalents, beginning of period	0	12
Cash and cash equivalents, end of period	0	0
Non-Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	446	90
Property and equipment additions	(18)	(16)
Proceeds received on asset sales	2	1
Payments to Acquire Restricted Investments	(36)	(124)
Other, net	0	0
Net cash used in investing activities exclusive of vehicle programs	(52)	(139)
Decrease (increase) in program cash	51	12
Investment in vehicles	(3,192)	(3,266)
Proceeds received on disposition of vehicles	2,440	2,467
Net cash used in investing activities of vehicle programs	(701)	(787)
Net cash used in investing activities	(753)	(926)
Proceeds from long-term borrowings	1	295
Principal payments on borrowings	(1)	0
Net change in short-term borrowings	(7)	11
Intercompany loan borrowings	24
Repurchases of common stock	0	0
Debt financing fees	0	(5)
Other, net	(1)	0
Net cash provided by financing activities exclusive of vehicle programs	16	301
Proceeds from borrowings	3,667	3,775
Principal payments on borrowings	(3,456)	(3,280)
Debt financing fees	(6)	(7)
Net cash provided by financing activities of vehicle programs	205	488
Net cash provided by financing activities	221	789
Effect of changes in exchange rates on cash and cash equivalents	(26)	(1)
Net increase in cash and cash equivalents	(112)	(48)
Cash and cash equivalents, beginning of period	412	425
Cash and cash equivalents, end of period	300	377
Eliminations [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	0	0
Property and equipment additions	0	0
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Intercompany loan advances	24
Other, net	(34)	(57)
Net cash used in investing activities exclusive of vehicle programs	(10)	(57)
Decrease (increase) in program cash	0	0
Investment in vehicles	0	0
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	0	0
Net cash used in investing activities	(10)	(57)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Intercompany loan borrowings	(24)
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	34	57
Net cash provided by financing activities exclusive of vehicle programs	10	57
Proceeds from borrowings	0	0
Principal payments on borrowings	0	0
Debt financing fees	0	0
Net cash provided by financing activities of vehicle programs	0	0
Net cash provided by financing activities	10	57
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	$ 0	$ 0