Receivables - Schedule of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Customer receivables
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 13	$ 8	$ 6
Provision for doubtful accounts	1	7	4
Write off of uncollectible accounts	(5)	(3)	(2)
Recoveries of prior write-offs	0	(1)	0
Other	(1)	2	0
Balance at end of year	8	13	8
Other receivables
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	32	34	24
Provision for doubtful accounts	9	6	8
Write off of uncollectible accounts	(1)	(1)	2
Recoveries of prior write-offs	(3)	1	(1)
Other	(3)	(8)	1
Balance at end of year	$ 34	$ 32	$ 34