Receivables, Net - Rollforward of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance For Doubtful Accounts Receivable Rollforward
Beginning balance	$ 34	$ 38	$ 19
Additions charged to expenses	3	17	27
Charge-offs and other	(8)	(21)	(8)
Ending balance	$ 29	$ 34	$ 38