Interest Cost Components - Schedule of Interest Cost Components (Detail) - USD ($) $ in Millions		12 Months Ended
	Jun. 19, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Amount charged to expense	$ 24	$ 496	$ 499	$ 473
Amount capitalized		22	32	27
Interest costs		$ 518	$ 531	$ 500