Other Financial Information - Schedule of Cash Paid for Interest and Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Financial Information [Abstract]
Interest, net of amount capitalized	$ 111	$ 100	$ 226
Income taxes, net of amount refunded	$ 507	$ 363	$ 265