Stockholders' Equity (Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders Equity [Line Items]
Currency Translation Adjustments, Balance			$ 9	$ (3)
Net Unrealized Gains (Losses) on Cash Flow Hedges, Balance	$ (53)	$ (22)	(53)	(22)
Currency Translation Adjustments, Balance			(146)	(132)
Accumulated Other Comprehensive Income, Balance			(157)	(133)
Currency Translation Adjustments, Current period change	35	(31)	(9)	(21)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(7)	(4)	(33)	(25)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(1)	(1)	(5)	(5)
Other comprehensive income (loss)	29	(34)	(37)	(41)
Currency Translation Adjustments, Balance	0	(24)	0	(24)
Net Unrealized Gains (Losses) on Cash Flow Hedges, Balance			(20)	2
Currency Translation Adjustments, Balance	(141)	(127)	(141)	(127)
Accumulated Other Comprehensive Income, Balance	(194)	(173)	(194)	(173)
Derivatives used in Net Investment Hedge, Net of Tax	47		47
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent			(9)	(21)
Other Comprehensive Income Unrealized Gain Loss On Cash Flow Hedges Arising During Period Net Of Tax			(38)	(23)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			(33)	(25)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Net of Tax			4	4
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(46)	(43)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			9	2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax			0	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax			(5)	2
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax			1	1
Corporate Interest Expense [Member]
Stockholders Equity [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	3	1	5	4
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	3	0	4	2
Selling, General and Administrative Expenses [Member]
Stockholders Equity [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	2	2	6	6
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	1	$ 1	4	4
Vehicle Interest Net [Member]
Stockholders Equity [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	1		2
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	$ 0		$ 1
Adjustments for New Accounting Pronouncement [Member]
Stockholders Equity [Line Items]
Currency Translation Adjustments, Balance				(3)
Currency Translation Adjustments, Balance				(132)
Accumulated Other Comprehensive Income, Balance				(132)
Net Unrealized Gains (Losses) on Cash Flow Hedges, Balance				3
Revision of Prior Period, Accounting Standards Update, Adjustment
Stockholders Equity [Line Items]
Currency Translation Adjustments, Balance				0
Currency Translation Adjustments, Balance				0
Accumulated Other Comprehensive Income, Balance				1
Net Unrealized Gains (Losses) on Cash Flow Hedges, Balance				$ 1