Guarantor And Non-Guarantor Consolidating Condensed Financial Statements (Consolidating Condensed Statements Of Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Revenues	$ 1,968	$ 1,839
Expenses
Operating	1,092	1,049
Vehicle depreciation and lease charges, net	515	504
Selling, general and administrative	296	262
Vehicle interest, net	72	64
Non-vehicle related depreciation and amortization	61	63
Interest expense	46	49
Intercompany interest expense (income)	0	0
Early extinguishment of debt	5	3
Restructuring and other related charges	6	7
Transaction-related costs, net	4	3
Total expenses	2,097	2,004
Income before income taxes	(129)	(165)
Provision for (benefit from) income taxes	42	58
Equity in earnings (loss) of subsidiaries	0	0
Net income (loss)	(87)	(107)
Comprehensive income (loss)	79	79
Eliminations [Member]
Revenues
Revenues	(575)	(585)
Expenses
Operating	0	0
Vehicle depreciation and lease charges, net	(525)	(535)
Selling, general and administrative	0	0
Vehicle interest, net	(50)	(50)
Non-vehicle related depreciation and amortization	0	0
Interest expense	0	0
Intercompany interest expense (income)	0	0
Early extinguishment of debt	0	0
Restructuring and other related charges	0	0
Transaction-related costs, net	0	0
Total expenses	(575)	(585)
Income before income taxes	0	0
Provision for (benefit from) income taxes	0	0
Equity in earnings (loss) of subsidiaries	(84)	(8)
Net income (loss)	(84)	(8)
Comprehensive income (loss)	94	88
Parent Company [Member]
Revenues
Revenues	0	0
Expenses
Operating	1	1
Vehicle depreciation and lease charges, net	0	0
Selling, general and administrative	18	10
Vehicle interest, net	0	0
Non-vehicle related depreciation and amortization	0	0
Interest expense	0	0
Intercompany interest expense (income)	(3)	(3)
Early extinguishment of debt	0	0
Restructuring and other related charges	0	0
Transaction-related costs, net	0	0
Total expenses	16	8
Income before income taxes	(16)	(8)
Provision for (benefit from) income taxes	6	2
Equity in earnings (loss) of subsidiaries	(77)	(101)
Net income (loss)	(87)	(107)
Comprehensive income (loss)	79	79
Subsidiaries [Member]
Revenues
Revenues	0	0
Expenses
Operating	4	4
Vehicle depreciation and lease charges, net	0	0
Selling, general and administrative	3	2
Vehicle interest, net	0	0
Non-vehicle related depreciation and amortization	0	0
Interest expense	39	46
Intercompany interest expense (income)	22	1
Early extinguishment of debt	5	3
Restructuring and other related charges	0	0
Transaction-related costs, net	0	0
Total expenses	73	56
Income before income taxes	(73)	(56)
Provision for (benefit from) income taxes	19	23
Equity in earnings (loss) of subsidiaries	(23)	(68)
Net income (loss)	(77)	(101)
Comprehensive income (loss)	69	74
Guarantor Subsidiaries [Member]
Revenues
Revenues	1,184	1,153
Expenses
Operating	621	640
Vehicle depreciation and lease charges, net	536	546
Selling, general and administrative	155	153
Vehicle interest, net	52	45
Non-vehicle related depreciation and amortization	36	40
Interest expense	1	1
Intercompany interest expense (income)	6	6
Early extinguishment of debt	0	0
Restructuring and other related charges	3	6
Transaction-related costs, net	0	0
Total expenses	1,410	1,437
Income before income taxes	(226)	(284)
Provision for (benefit from) income taxes	19	39
Equity in earnings (loss) of subsidiaries	184	177
Net income (loss)	(23)	(68)
Comprehensive income (loss)	21	41
Non-Guarantor Subsidiaries [Member]
Revenues
Revenues	1,359	1,271
Expenses
Operating	466	404
Vehicle depreciation and lease charges, net	504	493
Selling, general and administrative	120	97
Vehicle interest, net	70	69
Non-vehicle related depreciation and amortization	25	23
Interest expense	6	2
Intercompany interest expense (income)	(25)	(4)
Early extinguishment of debt	0	0
Restructuring and other related charges	3	1
Transaction-related costs, net	4	3
Total expenses	1,173	1,088
Income before income taxes	186	183
Provision for (benefit from) income taxes	(2)	(6)
Equity in earnings (loss) of subsidiaries	0	0
Net income (loss)	184	177
Comprehensive income (loss)	$ (184)	$ (203)