Intangible Assets (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Document Period End Date			Jun. 30, 2017
Amortization expense relating to all intangible assets	$ 16	$ 16	$ 31	$ 33
Amortization expense for remainder of the year	29		$ 29
Document Fiscal Year Focus			2017
Intangible assets amortization expense, year one	45		$ 45
Intangible assets amortization expense, year two	40		40
Intangible assets amortization expense, year three	39		39
Intangible assets amortization expense, year four	29		29
Intangible assets amortization expense, year five	$ 23		$ 23