Consolidating Condensed Statements of Cash Flows (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		$ 2,584	$ 2,579	$ 2,253
Investing activities
Property and equipment additions		(199)	(182)	(152)
Proceeds received on asset sales		15	21	22
Net assets acquired (net of cash acquired)		(256)	(416)	(537)
intercompany loan receipts		0		0
Other, net		6	(11)	2
Net cash used in investing activities exclusive of vehicle programs		(434)	(588)	(665)
Vehicle programs:
Decrease in program cash		(148)	(10)	(79)
Investment In Vehicles		(11,928)	(11,875)	(10,899)
Proceeds received on disposition of vehicles		9,680	9,666	9,409
Net Cash Used In Investing Activities Of Vehicle Programs		(2,396)	(2,219)	(1,569)
Net cash used in investing activities		(2,830)	(2,807)	(2,234)
Financing activities
Proceeds from borrowings		377	871	2,972
Principal payments on borrowings		(301)	(762)	(2,608)
Proceeds from (Repayments of) Short-term Debt		(22)	5	(36)
Debt financing fees		(7)	(17)	(37)
Purchase of warrants	$ (41)	0	0	(78)
Proceeds from sale of call options	54	0	0	104
Payments for Repurchase of Common Stock		(393)	(297)	(48)
Intercompany loan borrowings		0		0
Other, net		(7)	0	3
Net cash (used in) provided by financing activities exclusive of vehicle programs		(353)	(200)	272
Vehicle programs:
Proceeds from borrowings		14,138	14,373	12,953
Principal payments on borrowings		(13,648)	(13,963)	(13,115)
Debt financing fees		(22)	(28)	(34)
Net cash provided by financing activities of vehicle programs		468	382	(196)
Net cash provided by (used in) financing activities		115	182	76
Effect of changes in exchange rates on cash and cash equivalents		(41)	(23)	(8)
Net (decrease) increase in cash and cash equivalents		(172)	(69)	87
Cash and cash equivalents, beginning of period		624	693	606
Cash and cash equivalents, end of period	693	452	624	693
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		60	0	(3)
Investing activities
Property and equipment additions		0	0	0
Proceeds received on asset sales		0	0	0
Net assets acquired (net of cash acquired)		0	0	0
intercompany loan receipts		0		0
Other, net		334	285	146
Net cash used in investing activities exclusive of vehicle programs		334	285	146
Vehicle programs:
Decrease in program cash		0	0	0
Investment In Vehicles		0	0	0
Proceeds received on disposition of vehicles		0	0	0
Net Cash Used In Investing Activities Of Vehicle Programs		0	0	0
Net cash used in investing activities		334	285	146
Financing activities
Proceeds from borrowings		0	0	0
Principal payments on borrowings		0	0	(115)
Proceeds from (Repayments of) Short-term Debt		0	0	0
Debt financing fees		0	0	0
Purchase of warrants				(78)
Proceeds from sale of call options				104
Payments for Repurchase of Common Stock		(393)	(297)	(48)
Intercompany loan borrowings		0		0
Other, net		1	0	3
Net cash (used in) provided by financing activities exclusive of vehicle programs		(392)	(297)	(134)
Vehicle programs:
Proceeds from borrowings		0	0	0
Principal payments on borrowings		0	0	0
Debt financing fees		0	0	0
Net cash provided by financing activities of vehicle programs		0	0	0
Net cash provided by (used in) financing activities		(392)	(297)	(134)
Effect of changes in exchange rates on cash and cash equivalents		0	0	0
Net (decrease) increase in cash and cash equivalents		2	(12)	9
Cash and cash equivalents, beginning of period		2	14	5
Cash and cash equivalents, end of period	14	4	2	14
Subsidiary Issuers
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		249	469	562
Investing activities
Property and equipment additions		(26)	(20)	(26)
Proceeds received on asset sales		7	7	7
Net assets acquired (net of cash acquired)		(8)	0	(564)
intercompany loan receipts		(30)		233
Other, net		(127)	(9)	(50)
Net cash used in investing activities exclusive of vehicle programs		(184)	(22)	(400)
Vehicle programs:
Decrease in program cash		0	0	0
Investment In Vehicles		(1)	(9)	(44)
Proceeds received on disposition of vehicles		19	8	40
Net Cash Used In Investing Activities Of Vehicle Programs		18	(1)	(4)
Net cash used in investing activities		(166)	(23)	(404)
Financing activities
Proceeds from borrowings		375	575	2,647
Principal payments on borrowings		(256)	(756)	(2,489)
Proceeds from (Repayments of) Short-term Debt		0	0	0
Debt financing fees		(7)	(12)	(30)
Purchase of warrants				0
Proceeds from sale of call options				0
Payments for Repurchase of Common Stock		0	0	0
Intercompany loan borrowings		0		0
Other, net		(335)	(285)	(146)
Net cash (used in) provided by financing activities exclusive of vehicle programs		(223)	(478)	(18)
Vehicle programs:
Proceeds from borrowings		0	0	0
Principal payments on borrowings		0	0	0
Debt financing fees		0	0	0
Net cash provided by financing activities of vehicle programs		0	0	0
Net cash provided by (used in) financing activities		(223)	(478)	(18)
Effect of changes in exchange rates on cash and cash equivalents		0	0	0
Net (decrease) increase in cash and cash equivalents		(140)	(32)	140
Cash and cash equivalents, beginning of period		210	242	102
Cash and cash equivalents, end of period	242	70	210	242
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		146	340	26
Investing activities
Property and equipment additions		(98)	(84)	(69)
Proceeds received on asset sales		1	8	4
Net assets acquired (net of cash acquired)		(9)	(263)	8
intercompany loan receipts		(96)		60
Other, net		1	(2)	48
Net cash used in investing activities exclusive of vehicle programs		(201)	(341)	51
Vehicle programs:
Decrease in program cash		0	0	0
Investment In Vehicles		(2)	(90)	(2)
Proceeds received on disposition of vehicles		0	0	0
Net Cash Used In Investing Activities Of Vehicle Programs		(2)	(90)	(2)
Net cash used in investing activities		(203)	(431)	49
Financing activities
Proceeds from borrowings		0	0	0
Principal payments on borrowings		(4)	(5)	(3)
Proceeds from (Repayments of) Short-term Debt		0	0	0
Debt financing fees		0	0	0
Purchase of warrants				0
Proceeds from sale of call options				0
Payments for Repurchase of Common Stock		0	0	0
Intercompany loan borrowings		0		(60)
Other, net		70	0	0
Net cash (used in) provided by financing activities exclusive of vehicle programs		66	(5)	(63)
Vehicle programs:
Proceeds from borrowings		0	88	0
Principal payments on borrowings		(9)	(3)	0
Debt financing fees		0	(1)	0
Net cash provided by financing activities of vehicle programs		(9)	84	0
Net cash provided by (used in) financing activities		57	79	(63)
Effect of changes in exchange rates on cash and cash equivalents		0	0	0
Net (decrease) increase in cash and cash equivalents		0	(12)	12
Cash and cash equivalents, beginning of period		0	12	0
Cash and cash equivalents, end of period	12	0	0	12
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		2,204	1,840	1,736
Investing activities
Property and equipment additions		(75)	(78)	(57)
Proceeds received on asset sales		7	6	11
Net assets acquired (net of cash acquired)		(239)	(153)	19
intercompany loan receipts		0		0
Other, net		8	0	4
Net cash used in investing activities exclusive of vehicle programs		(299)	(225)	(23)
Vehicle programs:
Decrease in program cash		(148)	(10)	(79)
Investment In Vehicles		(11,925)	(11,776)	(10,853)
Proceeds received on disposition of vehicles		9,661	9,658	9,369
Net Cash Used In Investing Activities Of Vehicle Programs		(2,412)	(2,128)	(1,563)
Net cash used in investing activities		(2,711)	(2,353)	(1,586)
Financing activities
Proceeds from borrowings		2	296	325
Principal payments on borrowings		(41)	(1)	(1)
Proceeds from (Repayments of) Short-term Debt		$ (22)	5	(36)
Debt financing fees			(5)	(7)
Purchase of warrants				0
Proceeds from sale of call options				0
Payments for Repurchase of Common Stock		$ 0	0	0
Intercompany loan borrowings		126		(233)
Other, net		(28)	(70)	(68)
Net cash (used in) provided by financing activities exclusive of vehicle programs		37	225	(20)
Vehicle programs:
Proceeds from borrowings		14,138	14,285	12,953
Principal payments on borrowings		(13,639)	(13,960)	(13,115)
Debt financing fees		(22)	(27)	(34)
Net cash provided by financing activities of vehicle programs		477	298	(196)
Net cash provided by (used in) financing activities		514	523	(216)
Effect of changes in exchange rates on cash and cash equivalents		(41)	(23)	(8)
Net (decrease) increase in cash and cash equivalents		(34)	(13)	(74)
Cash and cash equivalents, beginning of period		412	425	499
Cash and cash equivalents, end of period	425	378	412	425
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		(75)	(70)	(68)
Investing activities
Property and equipment additions		0	0	0
Proceeds received on asset sales		0	0	0
Net assets acquired (net of cash acquired)		0	0	0
intercompany loan receipts		126		(293)
Other, net		(210)	(285)	(146)
Net cash used in investing activities exclusive of vehicle programs		(84)	(285)	(439)
Vehicle programs:
Decrease in program cash		0	0	0
Investment In Vehicles		0	0	0
Proceeds received on disposition of vehicles		0	0	0
Net Cash Used In Investing Activities Of Vehicle Programs		0	0	0
Net cash used in investing activities		(84)	(285)	(439)
Financing activities
Proceeds from borrowings		0	0	0
Principal payments on borrowings		0	0	0
Proceeds from (Repayments of) Short-term Debt		$ 0	0	0
Debt financing fees			0	0
Purchase of warrants				0
Proceeds from sale of call options				0
Payments for Repurchase of Common Stock		$ 0	0	0
Intercompany loan borrowings		(126)		293
Other, net		285	355	214
Net cash (used in) provided by financing activities exclusive of vehicle programs		159	355	507
Vehicle programs:
Proceeds from borrowings		0	0	0
Principal payments on borrowings		0	0	0
Debt financing fees		0	0	0
Net cash provided by financing activities of vehicle programs		0	0	0
Net cash provided by (used in) financing activities		159	355	507
Effect of changes in exchange rates on cash and cash equivalents		0	0	0
Net (decrease) increase in cash and cash equivalents		0	0	0
Cash and cash equivalents, beginning of period		0	0	0
Cash and cash equivalents, end of period	$ 0	$ 0	$ 0	$ 0