Stockholders' Equity (Narrative) (Detail) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($) shares
Stockholders Equity [Line Items]
Currency translation adjustments (net of tax of $(12), $(1), $(14), and $(6) respectively)	$ (31)	$ (8)	$ (21)	$ (61)
Stock Repurchased During Period, Shares | shares			2.1	3.5
Stock Repurchased During Period, Value			$ 59	$ 129
Other Comprehensive Income Unrealized Gain Loss On Cash Flow Hedges Arising During Period Net Of Tax			(23)	9
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax			(2)	(1)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			(25)	$ 8
Stock Repurchase Program, Authorized Amount	1,800		1,800
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 192		$ 192
Temporary Equity, Shares Outstanding | shares	0.6		0.6
Additional Paid-in Capital [Member]
Stockholders Equity [Line Items]
Option Premiums Paid			$ 16