Segment information - Reconciliation of Adjusted EBITDA to Net Income (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting [Abstract]
Consolidated Adjusted EBITDA	$ 420	$ 327	$ 1,509	$ 965
Impairment of non-current assets		3		10
Depreciation and amortization	203	163	621	525
Interest expense, net of capitalization	60	64	212	191
Income tax expense	53	56	329	103
Other income and (expense)	3	16	72	38
Earnings (losses) from equity method investments	2	(3)	4	(3)
Net Income	$ 109	$ 54	$ 423	$ 171