Fair Value Measurements - Fair Values of Derivative Instruments in Condensed Consolidated Balance Sheets (Detail) (Derivatives Designated as Hedging Instruments [Member], Interest rate contracts [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Derivatives Designated as Hedging Instruments [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Accounts Payable and Other Current Liabilities	$ 3	$ 6
Other Non-Current Liabilities	$ 15	$ 16