Stockholders' Equity (Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ (155)	$ 656
Other comprehensive income (loss) before reclassifications	19	(100)
Amounts reclassified from accumulated other comprehensive income (loss)	5	1
Net current-period other comprehensive income (loss)	24	(99)
Ending Balance	(316)	292
Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	40	9
Other comprehensive income (loss) before reclassifications	(14)	(83)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current-period other comprehensive income (loss)	(14)	(83)
Ending Balance	26	(74)
Net Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(51)	(20)
Other comprehensive income (loss) before reclassifications	32	(18)
Amounts reclassified from accumulated other comprehensive income (loss)	3	0
Net current-period other comprehensive income (loss)	35	(18)
Ending Balance	(16)	(38)
Net Unrealized Gains (Losses) on Cash Flow Hedges | Corporate Interest Expense
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive income (loss)	0
Reclassification before tax	1
Net Unrealized Gains (Losses) on Cash Flow Hedges | Vehicle Interest Net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive income (loss)	3
Reclassification before tax	4
Minimum Pension Liability Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(176)	(146)
Other comprehensive income (loss) before reclassifications	1	1
Amounts reclassified from accumulated other comprehensive income (loss)	2	1
Net current-period other comprehensive income (loss)	3	2
Ending Balance	(173)	(144)
Minimum Pension Liability Adjustment | Selling, General and Administrative Expenses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive income (loss)	2	1
Reclassification before tax	3	2
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(187)	(157)
Net current-period other comprehensive income (loss)	24	(99)
Ending Balance	(163)	$ (256)
Accumulated Gain Loss, Net, Net Investment Hedge, Attributable To Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Ending Balance	$ 47