SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Materials and supplies inventory allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 26		$ 26		$ 21
Additions Charged to Cost and Expense	7		4		11
Additons Charged to Other Accounts	0		0		0
Other Additions (Deductions)	(6)	[1]	(4)	[1]	(6)	[1]
Balance at End of Year	27		26		26
Valuation allowance for deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	2,393		2,226		2,157
Additions Charged to Cost and Expense	49		146		55
Additons Charged to Other Accounts	1		21		14
Other Additions (Deductions)	0		0		0
Balance at End of Year	2,443		2,393		2,226
Reserves for non-income taxes
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	73		73		47
Additions Charged to Cost and Expense	21		12		29
Additons Charged to Other Accounts	(2)		(2)		0
Other Additions (Deductions)	(12)	[2]	(10)	[2]	(3)	[2]
Balance at End of Year	$ 80		$ 73		$ 73

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

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