Stockholders' Equity (Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 92	$ (153)	$ (155)	$ 656
Other comprehensive income (loss) before reclassifications			(15)	(46)
Amounts reclassified from accumulated other comprehensive income (loss)			26	9
Net current-period other comprehensive income (loss)	(15)	29	11	(37)
Ending balance	(198)	(76)	(198)	(76)
Foreign exchange contracts | Derivatives designated as hedging instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Derivatives used in net investment hedge, net of tax	56		56
Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			40	9
Other comprehensive income (loss) before reclassifications			(33)	(9)
Amounts reclassified from accumulated other comprehensive income (loss)			11	0
Net current-period other comprehensive income (loss)			(22)	(9)
Ending balance	18	0	18	0
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			17	(38)
Amounts reclassified from accumulated other comprehensive income (loss)			10	5
Net current-period other comprehensive income (loss)			27	(33)
Ending balance	(24)	(53)	(24)	(53)
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)	(3)	(3)	(9)	(4)
Amounts reclassified from accumulated other comprehensive income (loss)	4	3	12	5
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)	(1)	0	(1)	(1)
Amounts reclassified from accumulated other comprehensive income (loss)	1	1	2	2
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)			5	4
Net current-period other comprehensive income (loss)			6	5
Ending balance	(170)	(141)	(170)	(141)
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)	(5)	(4)
Amounts reclassified from accumulated other comprehensive income (loss)	2	2	7	6
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(187)	(157)
Ending balance	$ (176)	$ (194)	$ (176)	$ (194)