Schedule II Valuation and Qualifying Accounts (Detail) (Accounts Receivable Allowances [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts Receivable Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 7	$ 10	$ 10
Additions Charged to Costs, Expenses or Other Accounts	9	7	12
Deductions	(9)	(10)	(12)
Balance at End of Period	$ 7	$ 7	$ 10