Equity Affiliates - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Dividends received from equity affiliates	$ 3	$ 4	$ 2
Threshold for reporting equity method investments	5
Equity method investment carrying amount over the book value	81
Equity method investment attributable to goodwill	$ 47
Other Than Goodwill | Minimum
Schedule of Equity Method Investments [Line Items]
Estimated useful life	5 years
Other Than Goodwill | Maximum
Schedule of Equity Method Investments [Line Items]
Estimated useful life	45 years