Schedule of Intangible Assets Amortization Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended					12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 4	$ 4	$ 3	$ 5	$ 4	$ 21	$ 7	$ 3
License Agreements
Finite-Lived Intangible Assets [Line Items]
Amortization expense						13	4	2
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Amortization expense						$ 8	$ 3	$ 1