Net Interest Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest Income Expense Net
Interest costs	$ 107	$ 197	$ 237
Interest costs capitalized	(18)	(51)	(70)
Interest expense	89	146	167
Interest income	(23)	(20)	(22)
Net interest expense	$ 66	$ 126	$ 145