Goodwill and Identifiable Intangible Assets - Amortization Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 47	$ 54	$ 46