Guarantor and Non-Guarantor Condensed Consolidating Financial Statements (Statement of Operations and Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Total revenues	$ 2,542	$ 2,575	$ 6,794	$ 6,991
Expenses:
Direct vehicle and operating	1,353	1,345	3,778	3,838
Depreciation of revenue earning vehicles and lease charges, net	695	631	1,940	1,859
Selling, general and administrative	227	218	685	692
Interest expense, net	156	153	480	447
Other (income) expense, net	3	(28)	(86)	(30)
Total expenses	2,434	2,319	6,797	6,806
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of subsidiaries	108	256	(3)	185
(Provision) benefit for taxes on income (loss) of continuing operations	(64)	(39)	(33)	(33)
Equity in earnings (losses) of subsidiaries, net of tax	0	0	0	0
Net income (loss) from continuing operations	44	217	(36)	152
Less: Net income (loss) from discontinued operations	(2)	21	(13)	53
Net income (loss)	42	238	(49)	205
Other comprehensive income (loss), net of tax	18	(40)	27	(75)
Comprehensive income (loss)	60	198	(22)	130
Eliminations
Condensed Financial Statements, Captions [Line Items]
Total revenues	(1,028)	(842)	(2,691)	(2,020)
Expenses:
Direct vehicle and operating	0	(1)	(1)	(2)
Depreciation of revenue earning vehicles and lease charges, net	(1,028)	(841)	(2,688)	(2,017)
Selling, general and administrative	0	0	(2)	(1)
Interest expense, net	0	0	0	0
Other (income) expense, net	0	0	0	0
Total expenses	(1,028)	(842)	(2,691)	(2,020)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of subsidiaries	0	0	0	0
(Provision) benefit for taxes on income (loss) of continuing operations	0	0	0	0
Equity in earnings (losses) of subsidiaries, net of tax	(382)	(607)	(1,127)	(1,102)
Net income (loss) from continuing operations	(382)	(607)	(1,127)	(1,102)
Less: Net income (loss) from discontinued operations	0	0	0	0
Net income (loss)	(382)	(607)	(1,127)	(1,102)
Other comprehensive income (loss), net of tax	(16)	39	(40)	82
Comprehensive income (loss)	(398)	(568)	(1,167)	(1,020)
Parent
Condensed Financial Statements, Captions [Line Items]
Total revenues	1,273	1,271	3,532	3,567
Expenses:
Direct vehicle and operating	782	765	2,200	2,180
Depreciation of revenue earning vehicles and lease charges, net	871	650	2,252	1,539
Selling, general and administrative	153	133	456	405
Interest expense, net	103	98	310	290
Other (income) expense, net	3	10	4	8
Total expenses	1,912	1,656	5,222	4,422
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of subsidiaries	(639)	(385)	(1,690)	(855)
(Provision) benefit for taxes on income (loss) of continuing operations	416	151	831	206
Equity in earnings (losses) of subsidiaries, net of tax	265	472	810	854
Net income (loss) from continuing operations	42	238	(49)	205
Less: Net income (loss) from discontinued operations	0	0	0	0
Net income (loss)	42	238	(49)	205
Other comprehensive income (loss), net of tax	18	(40)	27	(75)
Comprehensive income (loss)	60	198	(22)	130
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Total revenues	425	439	1,150	1,230
Expenses:
Direct vehicle and operating	206	218	587	664
Depreciation of revenue earning vehicles and lease charges, net	192	210	540	470
Selling, general and administrative	12	13	36	57
Interest expense, net	(17)	(9)	(39)	(19)
Other (income) expense, net	0	0	(10)	(1)
Total expenses	393	432	1,114	1,171
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of subsidiaries	32	7	36	59
(Provision) benefit for taxes on income (loss) of continuing operations	(26)	2	(28)	(10)
Equity in earnings (losses) of subsidiaries, net of tax	117	135	317	248
Net income (loss) from continuing operations	123	144	325	297
Less: Net income (loss) from discontinued operations	(2)	24	(3)	56
Net income (loss)	121	168	322	353
Other comprehensive income (loss), net of tax	0	0	(5)	(4)
Comprehensive income (loss)	121	168	317	349
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Total revenues	1,872	1,707	4,803	4,214
Expenses:
Direct vehicle and operating	365	363	992	996
Depreciation of revenue earning vehicles and lease charges, net	660	612	1,836	1,867
Selling, general and administrative	62	72	195	231
Interest expense, net	70	64	209	176
Other (income) expense, net	0	(38)	(80)	(37)
Total expenses	1,157	1,073	3,152	3,233
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of subsidiaries	715	634	1,651	981
(Provision) benefit for taxes on income (loss) of continuing operations	(454)	(192)	(836)	(229)
Equity in earnings (losses) of subsidiaries, net of tax	0	0	0	0
Net income (loss) from continuing operations	261	442	815	752
Less: Net income (loss) from discontinued operations	0	(3)	(10)	(3)
Net income (loss)	261	439	805	749
Other comprehensive income (loss), net of tax	16	(39)	45	(78)
Comprehensive income (loss)	$ 277	$ 400	$ 850	$ 671