Receivables - Schedule of Allowance for Doubtful Accounts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Customer Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	$ 46	$ 46
Provision for doubtful accounts	2	19
Write off of uncollectible accounts	(8)	(14)
Recoveries of prior write-offs	(1)	(3)
Other		(2)
Balance at end of year	39	46
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	79	87
Provision for doubtful accounts	9	7
Write off of uncollectible accounts	(3)	(3)
Recoveries of prior write-offs	(6)	(5)
Other	(5)	(7)
Balance at end of year	$ 74	$ 79