SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Part 3 (Details) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
REGULATED OPERATIONS [Abstract]
Regulatory Assets	$ 496,721,000	$ 449,211,000
Regulatory Liabilities	59,432,000	54,172,000
Regulatory Assets - Non-current	456,047,000	423,492,000
NATURAL GAS STORED UNDERGROUND [Abstract]
The amount by which the replacement cost is less than the cost basis value of stored gas inventories	(24,300,000)	(19,900,000)
REVENUE RECOGNITION [Abstract]
Accrued Unbilled Revenue	11,600,000	11,800,000
Unamortized Investment Tax Credits [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Liabilities	3,113,000	3,326,000
Accrued cost of removal [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Liabilities	55,103,000	49,380,000
Other Regulatory Liabilities [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Liabilities	1,216,000	1,466,000
Future Income Taxes Due From Customers [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	118,997,000	106,460,000
Pension And Postretirement Cost [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	304,446,000	272,126,000
Unamortized Purchased Gas Adjustments Asset [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	40,674,000	25,719,000
Purchased Gas Costs [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	18,386,000	29,476,000
Compensated Absences Cost [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	7,836,000	7,769,000
Cold Weather Rule [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	0	2,023,000
Other Regulatory Assets [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets	6,382,000	5,638,000
Deferred Costs Incurred Prior to YE 1999 [Member]
REGULATED OPERATIONS [Abstract]
Regulatory Assets - Non-current	10,500,000
Amortization period of deferred costs (in years)	fifteen-year
Amortization of deferred costs recognized to date - total	$ 9,000,000