DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	Mar. 31, 2012		Dec. 31, 2011
Derivative [Line Items]
Commodity and other energy management contracts designated as cash flow hedges (in DT)	31,733,275		36,427,763
Nonmonetary Notional Amount of Price Risk Derivative Instruments Not Designated as Hedging Instruments	40,527,609	[1]	41,023,563	[2]
Commodity and other energy management contracts (in DT)	72,260,884	[1]	77,451,326	[2]
Commodity and other energy management contracts not designated as hedges (in DT)	8,694,000		9,626,000
Aggregate notional amount of interest rate swaps designated as fair value hedge (in dollars)	$ 0		$ 0
Aggregate notional amount of interest rate swaps designated as cash flow hedge (in dollars)	$ 322.6		$ 822.6
Gas Distribution
Derivative [Line Items]
Commodity and other energy management contracts designated as cash flow hedges (in DT)	0		0
Nonmonetary Notional Amount of Price Risk Derivative Instruments Not Designated as Hedging Instruments	10,100,000		9,080,000
Commodity and other energy management contracts (in DT)	10,100,000		9,080,000
Retail Gas Marketing
Derivative [Line Items]
Commodity and other energy management contracts designated as cash flow hedges (in DT)	4,141,000		6,566,000
Nonmonetary Notional Amount of Price Risk Derivative Instruments Not Designated as Hedging Instruments	0		0
Commodity and other energy management contracts (in DT)	4,141,000		6,566,000
Energy Marketing
Derivative [Line Items]
Commodity and other energy management contracts designated as cash flow hedges (in DT)	27,592,275		29,861,763
Nonmonetary Notional Amount of Price Risk Derivative Instruments Not Designated as Hedging Instruments	30,427,609	[1]	31,943,563	[2]
Commodity and other energy management contracts (in DT)	58,019,884	[1]	61,805,326	[2]

[1] (a) Includes an aggregate 8,694,000 DT related to basis swap contracts in Energy Marketing.

[2] (b) Includes an aggregate 9,626,000 DT related to basis swap contracts in Energy Marketing.