Acquisitions and Divestitures - Adjustments to Preliminary Purchase Price Allocation (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012 Oakleaf [Member]	Sep. 30, 2011 Oakleaf [Member]	Sep. 30, 2012 Adjustments [Member]
Business Acquisition [Line Items]
Accounts and other receivables				$ 71	$ 68	$ 3
Other current assets				28	28
Property and equipment	126	225	279	70	77	(7)
Goodwill	69	497	77	328	320	8
Other intangible assets				87	92	(5)
Accounts payable	(8)	(7)	(5)	(82)	(80)	(2)
Accrued liabilities				(48)	(48)
Deferred income taxes, net				(9)	(13)	4
Other liabilities				(13)	(12)	(1)
Total purchase price				$ 432	$ 432