Consolidating Condensed Statements of Operations (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended							12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Revenues
Vehicle rental								$ 5,297	$ 4,338		$ 3,882
Other								2,060	1,562		1,303
Net revenues								7,357	5,900		5,185
Expenses
Operating								3,824	3,025		2,616
Vehicle depreciation and lease charges, net								1,471	1,223		1,287
Selling, general and administrative								925	756		569
Vehicle interest, net								297	286		304
Non-vehicle related depreciation and amortization								125	95		90
Interest expense related to corporate debt, net:
Interest expense						7	7	268	219		170
Early extinguishment of debt								75			52
Transaction-related costs								34	255		14
Restructuring charges	12	7	12	7	5			38	5		11
Total expenses								7,057	5,864		5,113
Income (loss) before income taxes and equity in earnings of subsidiaries								300	36		72
Provision for (benefit) from income taxes								10	65		18
Net income (loss)								290	(29)	[1]	54
Comprehensive income								322	(43)		183
Parent Company
Revenues
Other								1	2		4
Net revenues								1	2		4
Expenses
Operating									3		5
Selling, general and administrative								21	11		11
Interest expense related to corporate debt, net:
Interest expense								9	10		9
Intercompany interest expense (income)								(18)	(14)		(14)
Early extinguishment of debt								44
Transaction-related costs								4	71		14
Total expenses								60	81		25
Income (loss) before income taxes and equity in earnings of subsidiaries								(59)	(79)		(21)
Provision for (benefit) from income taxes								(8)	(27)		(9)
Equity in earnings (loss) of subsidiaries								341	23		66
Net income (loss)								290	(29)		54
Comprehensive income								322	(43)		183
Subsidiary Issuers
Expenses
Operating								5	8		8
Vehicle interest, net									(1)
Non-vehicle related depreciation and amortization								2
Interest expense related to corporate debt, net:
Interest expense								246	208		163
Intercompany interest expense (income)								(314)	(205)		(215)
Early extinguishment of debt								31			52
Transaction-related costs								1	56
Total expenses								(29)	66		8
Income (loss) before income taxes and equity in earnings of subsidiaries								29	(66)		(8)
Provision for (benefit) from income taxes								(106)	(22)		(8)
Equity in earnings (loss) of subsidiaries								206	67		66
Net income (loss)								341	23		66
Comprehensive income								373	7		195
Guarantor Subsidiaries
Revenues
Vehicle rental								3,491	3,393		3,261
Other								1,052	1,006		922
Net revenues								4,543	4,399		4,183
Expenses
Operating								2,305	2,241		2,084
Vehicle depreciation and lease charges, net								902	921		1,085
Selling, general and administrative								573	564		473
Vehicle interest, net								234	243		283
Non-vehicle related depreciation and amortization								75	78		83
Interest expense related to corporate debt, net:
Intercompany interest expense (income)								277	215		229
Transaction-related costs								1
Restructuring charges								3	2		11
Total expenses								4,370	4,264		4,248
Income (loss) before income taxes and equity in earnings of subsidiaries								173	135		(65)
Provision for (benefit) from income taxes								72	66		(5)
Equity in earnings (loss) of subsidiaries								105	(2)		126
Net income (loss)								206	67		66
Comprehensive income								237	50		174
Non-Guarantor Subsidiaries
Revenues
Vehicle rental								1,806	945		621
Other								2,130	1,702		1,672
Net revenues								3,936	2,647		2,293
Expenses
Operating								1,514	773		519
Vehicle depreciation and lease charges, net								996	868		1,070
Selling, general and administrative								331	181		85
Vehicle interest, net								300	296		146
Non-vehicle related depreciation and amortization								48	17		7
Interest expense related to corporate debt, net:
Interest expense								13	1		(2)
Intercompany interest expense (income)								55	4
Transaction-related costs								28	128
Restructuring charges								35	3
Total expenses								3,320	2,271		1,825
Income (loss) before income taxes and equity in earnings of subsidiaries								616	376		468
Provision for (benefit) from income taxes								52	48		40
Net income (loss)								564	328		428
Comprehensive income								594	358		542
Eliminations
Revenues
Other								(1,123)	(1,148)		(1,295)
Net revenues								(1,123)	(1,148)		(1,295)
Expenses
Vehicle depreciation and lease charges, net								(427)	(566)		(868)
Vehicle interest, net								(237)	(252)		(125)
Interest expense related to corporate debt, net:
Total expenses								(664)	(818)		(993)
Income (loss) before income taxes and equity in earnings of subsidiaries								(459)	(330)		(302)
Equity in earnings (loss) of subsidiaries								(652)	(88)		(258)
Net income (loss)								(1,111)	(418)		(560)
Comprehensive income								$ (1,204)	$ (415)		$ (911)

[1] As the Company incurred a net loss in 2011, all outstanding stock options, restricted stock units, stock warrants and issuable shares underlying the convertible notes have an anti-dilutive effect and therefore are excluded from the computation of diluted weighted average shares outstanding. Accordingly, basic and diluted weighted average shares outstanding are equal for such period.