Interest Cost Components - Schedule of Interest Cost Components (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Amount charged to expense	$ 499	$ 473	$ 442
Amount capitalized	32	27	22
Interest costs, total	$ 531	$ 500	$ 464