Guarantor And Non-Guarantor Consolidating Condensed Financial Statements (Consolidating Condensed Statements Of Cash Flows) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 463	$ 503
Property and equipment additions	(40)	(41)
Proceeds received on asset sales	3	3
Payments to Acquire Restricted Investments	(1)	(36)
Other, net	0	0
Net cash used in investing activities exclusive of vehicle programs	(38)	(74)
Decrease (increase) in program cash	198	51
Investment in vehicles	(4,140)	(3,195)
Proceeds received on disposition of vehicles	2,776	2,444
Net cash used in investing activities of vehicle programs	(1,166)	(700)
Net cash used in investing activities	(1,204)	(774)
Proceeds from long-term borrowings	350	376
Principal payments on borrowings	(5)	(6)
Net change in short-term borrowings	1	(7)
Intercompany loan borrowings	0	0
Proceeds from (Repayments of) Related Party Debt	0	0
Repurchases of common stock	(86)	(33)
Debt financing fees	(5)	(6)
Other, net	0	0
Net cash provided by financing activities exclusive of vehicle programs	255	324
Proceeds from borrowings	4,694	3,667
Principal payments on borrowings	(3,796)	(3,458)
Debt financing fees	(6)	(6)
Net cash provided by financing activities of vehicle programs	892	203
Net cash provided by financing activities	1,147	527
Effect of changes in exchange rates on cash and cash equivalents	18	(26)
Net increase in cash and cash equivalents	424	230
Cash and cash equivalents, beginning of period	452	624
Cash and cash equivalents, end of period	876	854
Parent [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
Other, net	86	33
Net cash used in investing activities exclusive of vehicle programs	86	33
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	86	33
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Intercompany loan borrowings	0	0
Proceeds from (Repayments of) Related Party Debt	0	0
Repurchases of common stock	(86)	(33)
Debt financing fees	0	0
Other, net	0	0
Net cash provided by financing activities exclusive of vehicle programs	(86)	(33)
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	(86)	(33)
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	4	2
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	17	12
Property and equipment additions	(4)	(4)
Proceeds received on asset sales	2	1
Payments to Acquire Restricted Investments	0	0
Other, net	0	0
Net cash used in investing activities exclusive of vehicle programs	(2)	(3)
Decrease (increase) in program cash	0	0
Investment in vehicles	0	(3)
Proceeds received on disposition of vehicles	11	4
Net cash used in investing activities of vehicle programs	11	1
Net cash used in investing activities	9	(2)
Proceeds from long-term borrowings	350	375
Principal payments on borrowings	(4)	(4)
Net change in short-term borrowings	0	0
Intercompany loan borrowings	0	0
Proceeds from (Repayments of) Related Party Debt	0	0
Repurchases of common stock	0	0
Debt financing fees	(5)	(6)
Other, net	(86)	(33)
Net cash provided by financing activities exclusive of vehicle programs	255	332
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	255	332
Effect of changes in exchange rates on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	281	342
Cash and cash equivalents, beginning of period	70	210
Cash and cash equivalents, end of period	351	552
Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	(2)	45
Property and equipment additions	(21)	(19)
Proceeds received on asset sales	0	0
Payments to Acquire Restricted Investments	0	0
Other, net	0	1
Net cash used in investing activities exclusive of vehicle programs	6	(42)
Decrease (increase) in program cash	0	0
Investment in vehicles	(1)	0
Proceeds received on disposition of vehicles	0	0
Net cash used in investing activities of vehicle programs	(1)	0
Net cash used in investing activities	5	(42)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	(1)	(1)
Net change in short-term borrowings	0	0
Intercompany loan borrowings	0	0
Proceeds from (Repayments of) Related Party Debt	27	(24)
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)	(2)
Debt financing fees	0	0
Net cash provided by financing activities of vehicle programs	(2)	(2)
Net cash provided by financing activities	(3)	(3)
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
Non-Guarantor Subsidiaries [Member]
Supplemental Guarantor Financial Information [Line Items]
Net cash provided by (used in) operating activities	448	446
Property and equipment additions	(15)	(18)
Proceeds received on asset sales	1	2
Payments to Acquire Restricted Investments	(1)	(36)
Other, net	0	0
Net cash used in investing activities exclusive of vehicle programs	(15)	(52)
Decrease (increase) in program cash	198	51
Investment in vehicles	(4,139)	(3,192)
Proceeds received on disposition of vehicles	2,765	2,440
Net cash used in investing activities of vehicle programs	(1,176)	(701)
Net cash used in investing activities	(1,191)	(753)
Proceeds from long-term borrowings	$ 0	1
Principal payments on borrowings		(1)
Net change in short-term borrowings	$ 1	(7)
Intercompany loan borrowings	(27)	24
Proceeds from (Repayments of) Related Party Debt	0	0
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	0	(1)
Net cash provided by financing activities exclusive of vehicle programs	(26)	16
Proceeds from borrowings	4,694	3,667
Principal payments on borrowings	(3,794)	(3,456)
Debt financing fees	(6)	(6)
Net cash provided by financing activities of vehicle programs	894	205
Net cash provided by financing activities	868	221
Effect of changes in exchange rates on cash and cash equivalents	18	(26)
Net increase in cash and cash equivalents	143	(112)
Cash and cash equivalents, beginning of period	378	412
Cash and cash equivalents, end of period	521	300
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
Other, net	(86)	(34)
Net cash used in investing activities exclusive of vehicle programs	(113)	(10)
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	(113)	(10)
Proceeds from long-term borrowings	0	0
Principal payments on borrowings	0	0
Net change in short-term borrowings	0	0
Intercompany loan borrowings	27	(24)
Proceeds from (Repayments of) Related Party Debt	(27)	24
Repurchases of common stock	0	0
Debt financing fees	0	0
Other, net	86	34
Net cash provided by financing activities exclusive of vehicle programs	113	10
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	113	10
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