DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Derivatives designated as hedging instruments
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	$ 7	$ 9
Liability Derivatives Fair Value	49	89
Derivatives designated as hedging instruments | Interest rate contracts | Prepayments and other
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	2
Derivatives designated as hedging instruments | Interest rate contracts | Other deferred debits
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	4	7
Derivatives designated as hedging instruments | Interest rate contracts | Other current assets
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value		1
Derivatives designated as hedging instruments | Interest rate contracts | Other current liabilities
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives Fair Value	14	57
Derivatives designated as hedging instruments | Interest rate contracts | Other deferred credits
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives Fair Value	30	25
Derivatives designated as hedging instruments | Commodity contracts | Other current liabilities
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	1	1
Liability Derivatives Fair Value	3	5
Derivatives designated as hedging instruments | Commodity contracts | Other deferred credits
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives Fair Value	2	2
Derivatives not designated as hedging instruments
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	11	12
Liability Derivatives Fair Value	8	9
Derivatives not designated as hedging instruments | Commodity contracts | Prepayments and other
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	3	3
Derivatives not designated as hedging instruments | Other energy management contracts. | Prepayments and other
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	4	7
Liability Derivatives Fair Value		1
Derivatives not designated as hedging instruments | Other energy management contracts. | Other deferred debits
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	3	2
Liability Derivatives Fair Value	1
Derivatives not designated as hedging instruments | Other energy management contracts. | Other current liabilities
Fair value of energy-related derivatives and interest rate derivatives
Liability Derivatives Fair Value	4	6
Derivatives not designated as hedging instruments | Other energy management contracts. | Other deferred credits
Fair value of energy-related derivatives and interest rate derivatives
Asset Derivatives Fair Value	1
Liability Derivatives Fair Value	$ 3	$ 2