Intangible Assets (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Document Period End Date	Mar. 31, 2017
Amortization expense relating to all intangible assets	$ 15	$ 17
Amortization expense for remainder of the year	40
Intangible assets amortization expense, year one	41
Intangible assets amortization expense, year two	37
Intangible assets amortization expense, year three	37
Intangible assets amortization expense, year four	27
Intangible assets amortization expense, year five	$ 22