SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Materials and supplies allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, Beginning Balance	$ 26		$ 21		$ 22
Additions Charged to Cost and Expense	4		11		4
Additons Charged to Other Accounts	0		0		0
Other Add (Deduct)	(4)	[1]	(6)	[1]	(5)	[1]
Balance, Ending Balance	26		26		21
Valuation allowance for deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, Beginning Balance	2,226		2,157		1,763
Additions Charged to Cost and Expense	146		55		366
Additons Charged to Other Accounts	21		14		28
Other Add (Deduct)	0		0		0
Balance, Ending Balance	2,393		2,226		2,157
Reserves for non-income taxes
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, Beginning Balance	73		47		32
Additions Charged to Cost and Expense	12		29		15
Additons Charged to Other Accounts	(2)		0		3
Other Add (Deduct)	(10)	[2]	(3)	[2]	(3)	[2]
Balance, Ending Balance	$ 73		$ 73		$ 47

[1] Primarily represents write-offs of obsolete materials and supplies inventories.

[2] Represents amounts paid or adjustments to reserves based on revised estimates.