Intangible Assets (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Accounts Payable, Other, Current	$ 269	$ 231	$ 269	$ 231
Document Period End Date			Sep. 30, 2018
Amortization expense relating to all intangible assets	15	17	$ 48	48
Amortization expense for remainder of the year	17		$ 17
Document Fiscal Year Focus			2018
Intangible assets amortization expense, year one	52		$ 52
Intangible assets amortization expense, year two	45		45
Intangible assets amortization expense, year three	32		32
Intangible assets amortization expense, year four	26		26
Intangible assets amortization expense, year five	23		23
Other Receivables	$ 757	$ 707	$ 757	$ 707