DERIVATIVE FINANCIAL INSTRUMENTS (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) MMBTU	Dec. 31, 2017 MMBTU
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	64,855,232	61,719,890
Gas Distribution
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	7,050,000	6,430,000
Gas Marketing segment [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	57,805,232	55,289,890
Commodity Contract
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	23,906,000	19,863,000
Commodity Contract | Gas Distribution
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	7,050,000	6,430,000
Commodity Contract | Gas Marketing segment [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	16,856,000	13,433,000
Energy Related Derivative [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	40,949,232	41,856,890
Energy Related Derivative [Member] | Gas Distribution
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	0	0
Energy Related Derivative [Member] | Gas Marketing segment [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	40,949,232	41,856,890
Energy Related Derivative [Member] | Basis Swap [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,396,000	2,582,000