Basis Of Presentation And Recently Issued Accounting Pronouncements (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basis Of Presentation And Recently Issued Accounting Pronouncements [Abstract]
Net unrealized gain or loss on foreign-currency transactions of intercompany loan hedges	$ (2)	$ (1)	$ (2)	$ (8)
Employee Service Share Based Compensation Incremental Tax Benefit To Be Realized From Exercise Of Stock Awards	$ 56		56
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 10