DERIVATIVE INSTRUMENTS 3 (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Interest Rate Contracts [Abstract]
Losses recognized in OCI on effective portion	$ (1,765,000)		$ (391,000)		$ (2,407,000)		$ (705,000)
Losses reclassified from accumulated OCI into income	(385,000)	[1]	(237,000)	[1]	(1,122,000)	[1]	(705,000)	[1]
Gains or (losses) recognized in income on ineffective portion	0	[1]	0	[1]	0	[1]	0	[1]
Gain (loss) on energy related derivative instruments not designated as hedging instruments	(8,543,000)	[2]	(1,173,000)	[2]	(2,411,000)	[2]	(19,090,000)	[2]
Gain (loss) on interest rate derivative instruments not designated as hedging instruments	(309,000)	[1]	(412,000)	[1]	(298,000)	[1]	(1,250,000)	[1]
Derivative instruments not designated as hedging instruments, gain (loss), net	(8,852,000)		(1,585,000)		(2,709,000)		(20,340,000)
Realized losses, derivative instruments on energy-related contracts	2,400,000		5,500,000		9,500,000		17,800,000
Fair value derivative instruments with credit-risk-related features	11,200,000				11,200,000
Additional collateral, aggregate fair value	$ 8,100,000				$ 8,100,000

[1] Included in Interest Charges

[2] Included in Operating Revenues - Non Utility