Guarantor And Non-Guarantor Consolidating Condensed Financial Statements (Consolidating Condensed Statements Of Cash Flows) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 2,038	$ 2,067
Property and equipment additions	(126)	(127)
Proceeds received on asset sales	8	9
Payments to Acquire Restricted Investments	(225)	(149)
Other, net	3	(9)
Net cash used in investing activities exclusive of vehicle programs	(340)	(276)
Decrease (increase) in program cash	(71)	23
Investment in vehicles	(9,762)	(9,835)
Proceeds received on disposition of vehicles	6,756	6,535
Net cash used in investing activities of vehicle programs	(3,077)	(3,277)
Net cash used in investing activities	(3,417)	(3,553)
Proceeds from long-term borrowings	377	696
Principal payments on borrowings	(290)	(751)
Net change in short-term borrowings	(23)	(3)
Repurchases of common stock	(270)	(204)
Debt financing fees	(7)	(12)
Other, net	0	(1)
Net cash used in financing activities exclusive of vehicle programs	(213)	(275)
Proceeds from borrowings	11,532	11,862
Principal payments on borrowings	(9,933)	(10,050)
Debt financing fees	(17)	(17)
Net cash provided by financing activities of vehicle programs	1,582	1,795
Net cash provided by financing activities	1,369	1,520
Effect of changes in exchange rates on cash and cash equivalents	(29)	(14)
Net (decrease) increase in cash and cash equivalents	(39)	20
Cash and cash equivalents, beginning of period	624	693
Cash and cash equivalents, end of period	585	713
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	60	1
Property and equipment additions	0	0
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Other, net	212	191
Net cash used in investing activities exclusive of vehicle programs	212	191
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	212	191
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	(270)	(204)
Debt financing fees	0	0
Other, net	0	(1)
Net cash used in financing activities exclusive of vehicle programs	(270)	(205)
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	(270)	(205)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	2	(13)
Cash and cash equivalents, beginning of period	2	14
Cash and cash equivalents, end of period	4	1
Subsidiary Issuers [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	270	728
Property and equipment additions	(17)	(12)
Proceeds received on asset sales	4	3
Payments to Acquire Restricted Investments	(8)	0
Intercompany loan advances	(30)
Other, net	(107)	(8)
Net cash used in investing activities exclusive of vehicle programs	(158)	(17)
Decrease (increase) in program cash	0	0
Investment in vehicles	(1)	(6)
Proceeds received on disposition of vehicles	15	7
Net cash used in investing activities of vehicle programs	14	1
Net cash used in investing activities	(144)	(16)
Proceeds from long-term borrowings	375	400
Principal payments on borrowings	(253)	(747)
Net change in short-term borrowings	0	0
Repurchases of common stock	0	0
Debt financing fees	(7)	(7)
Other, net	(212)	(191)
Net cash used in financing activities exclusive of vehicle programs	(97)	(545)
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	(97)	(545)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	29	167
Cash and cash equivalents, beginning of period	210	242
Cash and cash equivalents, end of period	239	409
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	104	58
Property and equipment additions	(64)	(60)
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	(3)	0
Intercompany loan advances	(94)
Other, net	1	(1)
Net cash used in investing activities exclusive of vehicle programs	(160)	(61)
Decrease (increase) in program cash	0	0
Investment in vehicles	(3)	(91)
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	(3)	(91)
Net cash used in investing activities	(163)	(152)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	(4)	(4)
Net change in short-term borrowings	0	0
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	70	0
Net cash used in financing activities exclusive of vehicle programs	66	(4)
Proceeds from borrowings	0	88
Principal payments on borrowings	(7)	(1)
Debt financing fees	0	(1)
Net cash provided by financing activities of vehicle programs	(7)	86
Net cash provided by financing activities	59	82
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net (decrease) 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	1,604	1,280
Property and equipment additions	(45)	(55)
Proceeds received on asset sales	4	6
Payments to Acquire Restricted Investments	(214)	(149)
Other, net	3	0
Net cash used in investing activities exclusive of vehicle programs	(252)	(198)
Decrease (increase) in program cash	(71)	23
Investment in vehicles	(9,758)	(9,738)
Proceeds received on disposition of vehicles	6,741	6,528
Net cash used in investing activities of vehicle programs	(3,088)	(3,187)
Net cash used in investing activities	(3,340)	(3,385)
Proceeds from long-term borrowings	2	296
Principal payments on borrowings	(33)	0
Net change in short-term borrowings	(23)	(3)
Intercompany loan borrowings	124
Repurchases of common stock	0	0
Debt financing fees	0	(5)
Other, net	36	0
Net cash used in financing activities exclusive of vehicle programs	106	288
Proceeds from borrowings	11,532	11,774
Principal payments on borrowings	(9,926)	(10,049)
Debt financing fees	(17)	(16)
Net cash provided by financing activities of vehicle programs	1,589	1,709
Net cash provided by financing activities	1,695	1,997
Effect of changes in exchange rates on cash and cash equivalents	(29)	(14)
Net (decrease) increase in cash and cash equivalents	(70)	(122)
Cash and cash equivalents, beginning of period	412	425
Cash and cash equivalents, end of period	342	303
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	124
Other, net	(106)	(191)
Net cash used in investing activities exclusive of vehicle programs	18	(191)
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	18	(191)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Intercompany loan borrowings	(124)
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	106	191
Net cash used in financing activities exclusive of vehicle programs	(18)	191
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	(18)	191
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net (decrease) 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