Receivables - Schedule of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Customer Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	$ 14	$ 20	$ 39
Provision for doubtful accounts	5	2	3
Write off of uncollectible accounts	(4)	(3)	(19)
Recoveries of prior write-offs		(2)	(3)
Other	(2)	(3)
Balance at end of year	13	14	20
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	41	47	74
Provision for doubtful accounts	8	8	29
Write off of uncollectible accounts	(2)	(4)	(39)
Recoveries of prior write-offs	1	(7)	(10)
Other	1	(3)	(7)
Balance at end of year	$ 49	$ 41	$ 47