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, 2014	Sep. 30, 2013
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 2,067	$ 1,743
Property and equipment additions	(127)	(92)
Proceeds received on asset sales	9	13
Payments to Acquire Restricted Investments	(149)	(531)
Proceeds from (Repayments of) Related Party Debt		0
Other, net	(9)	37
Net cash used in investing activities exclusive of vehicle programs	(276)	(573)
Decrease (increase) in program cash	23	(173)
Investment in vehicles	(9,835)	(8,865)
Proceeds received on disposition of vehicles	6,535	6,393
Net cash used in investing activities of vehicle programs	(3,277)	(2,645)
Net cash used in investing activities	(3,553)	(3,218)
Proceeds from long-term borrowings	696	2,725
Principal payments on borrowings	(751)	(2,344)
Net change in short-term borrowings	(3)	(32)
Purchase of warrants	0	(30)
Proceeds from sale of call options	0	41
Repurchases of common stock	(204)	(21)
Net intercompany transactions		0
Debt financing fees	(12)	(36)
Other, net	(1)	2
Net cash (used in) provided by financing activities exclusive of vehicle programs	(275)	305
Proceeds from borrowings	11,862	10,266
Principal payments on borrowings	(10,050)	(9,079)
Debt financing fees	(17)	(26)
Net cash provided by financing activities of vehicle programs	1,795	1,161
Net cash provided by financing activities	1,520	1,466
Effect of changes in exchange rates on cash and cash equivalents	(14)	(8)
Net increase (decrease) in cash and cash equivalents	20	(17)
Cash and cash equivalents, beginning of period	693	606
Cash and cash equivalents, end of period	713	589
Parent [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	1	(5)
Property and equipment additions	0	0
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Proceeds from (Repayments of) Related Party Debt		0
Other, net	191	109
Net cash used in investing activities exclusive of vehicle programs	191	109
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	191	109
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	(94)
Net change in short-term borrowings	0	0
Purchase of warrants		(30)
Proceeds from sale of call options		41
Repurchases of common stock	(204)	(21)
Net intercompany transactions		0
Debt financing fees	0	0
Other, net	(1)	2
Net cash (used in) provided by financing activities exclusive of vehicle programs	(205)	(102)
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	(205)	(102)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	(13)	2
Cash and cash equivalents, beginning of period	14	5
Cash and cash equivalents, end of period	1	7
Subsidiary Issuers [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	728	455
Property and equipment additions	(12)	(17)
Proceeds received on asset sales	3	4
Payments to Acquire Restricted Investments	0	(563)
Proceeds from (Repayments of) Related Party Debt		70
Other, net	(8)	(13)
Net cash used in investing activities exclusive of vehicle programs	(17)	(519)
Decrease (increase) in program cash	0	0
Investment in vehicles	(6)	(40)
Proceeds received on disposition of vehicles	7	22
Net cash used in investing activities of vehicle programs	1	(18)
Net cash used in investing activities	(16)	(537)
Proceeds from long-term borrowings	400	2,400
Principal payments on borrowings	(747)	(2,248)
Net change in short-term borrowings	0	0
Purchase of warrants		0
Proceeds from sale of call options		0
Repurchases of common stock	0	0
Net intercompany transactions		0
Debt financing fees	(7)	(29)
Other, net	(191)	(109)
Net cash (used in) provided by financing activities exclusive of vehicle programs	(545)	14
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	(545)	14
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	167	(68)
Cash and cash equivalents, beginning of period	242	102
Cash and cash equivalents, end of period	409	34
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	58	2
Property and equipment additions	(60)	(43)
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	8
Proceeds from (Repayments of) Related Party Debt		0
Other, net	(1)	47
Net cash used in investing activities exclusive of vehicle programs	(61)	12
Decrease (increase) in program cash	0	0
Investment in vehicles	(91)	(2)
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	(91)	(2)
Net cash used in investing activities	(152)	10
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	(4)	(2)
Net change in short-term borrowings	0	0
Purchase of warrants		0
Proceeds from sale of call options		0
Repurchases of common stock	0	0
Net intercompany transactions		0
Debt financing fees	0	0
Other, net	0	0
Net cash (used in) provided by financing activities exclusive of vehicle programs	(4)	(2)
Proceeds from borrowings	88	0
Principal payments on borrowings	(1)	0
Debt financing fees	(1)	0
Net cash provided by financing activities of vehicle programs	86	0
Net cash provided by financing activities	82	(2)
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	(12)	10
Cash and cash equivalents, beginning of period	12	0
Cash and cash equivalents, end of period	0	10
Non-Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	1,280	1,294
Property and equipment additions	(55)	(32)
Proceeds received on asset sales	6	9
Payments to Acquire Restricted Investments	(149)	24
Proceeds from (Repayments of) Related Party Debt		0
Other, net	0	3
Net cash used in investing activities exclusive of vehicle programs	(198)	4
Decrease (increase) in program cash	23	(173)
Investment in vehicles	(9,738)	(8,823)
Proceeds received on disposition of vehicles	6,528	6,371
Net cash used in investing activities of vehicle programs	(3,187)	(2,625)
Net cash used in investing activities	(3,385)	(2,621)
Proceeds from long-term borrowings	296	325
Principal payments on borrowings	0	0
Net change in short-term borrowings	(3)	(32)
Purchase of warrants		0
Proceeds from sale of call options		0
Repurchases of common stock	0	0
Net intercompany transactions		(70)
Debt financing fees	(5)	(7)
Other, net	0	(3)
Net cash (used in) provided by financing activities exclusive of vehicle programs	288	213
Proceeds from borrowings	11,774	10,266
Principal payments on borrowings	(10,049)	(9,079)
Debt financing fees	(16)	(26)
Net cash provided by financing activities of vehicle programs	1,709	1,161
Net cash provided by financing activities	1,997	1,374
Effect of changes in exchange rates on cash and cash equivalents	(14)	(8)
Net increase (decrease) in cash and cash equivalents	(122)	39
Cash and cash equivalents, beginning of period	425	499
Cash and cash equivalents, end of period	303	538
Eliminations [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	0	(3)
Property and equipment additions	0	0
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Proceeds from (Repayments of) Related Party Debt		(70)
Other, net	(191)	(109)
Net cash used in investing activities exclusive of vehicle programs	(191)	(179)
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	(191)	(179)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Purchase of warrants		0
Proceeds from sale of call options		0
Repurchases of common stock	0	0
Net intercompany transactions		70
Debt financing fees	0	0
Other, net	191	112
Net cash (used in) provided by financing activities exclusive of vehicle programs	191	182
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	191	182
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase (decrease) 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