Intangible Assets (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization expense relating to all intangible assets	$ 14	$ 15
Amortization expense for remainder of the year	$ 38
Document Fiscal Year Focus	2018
Intangible assets amortization expense, year one	$ 46
Intangible assets amortization expense, year two	44
Intangible assets amortization expense, year three	31
Intangible assets amortization expense, year four	25
Intangible assets amortization expense, year five	$ 22