Consolidated Statements Of Operations - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 2,162	$ 2,753	$ 2,337	$ 1,920	$ 2,050	$ 2,778	$ 2,328	$ 1,968	$ 9,172	$ 9,124	$ 8,848
Expenses
Operating									4,698	4,639	4,472
Vehicle depreciation and lease charges, net									2,063	2,179	2,221
Selling, general and administrative									1,237	1,220	1,120
Vehicle interest, net									344	314	286
Non-vehicle related depreciation and amortization									263	256	259
Interest expense related to corporate debt, net:
Interest expense									178	188	188
Early extinguishment of debt									12	19	3
Restructuring and other related charges									80	22	63
Transaction-related costs, net									10	20	23
Impairment									0	0	2
Total expenses									8,885	8,857	8,637
Income before income taxes									287	267	211
Provision for (benefit from) income taxes									(15)	102	(150)
Net income	$ 142	$ 189	$ 62	$ (91)	$ 13	$ 213	$ 26	$ (87)	$ 302	$ 165	$ 361
Earnings per share
Basic	$ 1.92	$ 2.52	$ 0.81	$ (1.20)	$ 0.16	$ 2.71	$ 0.33	$ (1.08)	$ 4.01	$ 2.08	$ 4.32
Diluted	$ 1.90	$ 2.50	$ 0.81	$ (1.20)	$ 0.16	$ 2.68	$ 0.32	$ (1.08)	$ 3.98	$ 2.06	$ 4.25