EMPLOYEE BENEFIT PLANS, DEFINED BENEFIT PLANS (Details) (USD $)	12 Months Ended						12 Months Ended			12 Months Ended			12 Months Ended																12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2014 US Equity Securities [Member]	Sep. 30, 2013 US Equity Securities [Member]	Sep. 30, 2012 US Equity Securities [Member]	Sep. 30, 2014 International Securities [Member]	Sep. 30, 2013 International Securities [Member]	Sep. 30, 2012 International Securities [Member]	Sep. 30, 2014 Fixed Income Securities [Member]	Sep. 30, 2013 Fixed Income Securities [Member]	Sep. 30, 2012 Fixed Income Securities [Member]	Sep. 30, 2013 Pension [Member]		Sep. 30, 2012 Pension [Member]		Sep. 30, 2011 Pension [Member]		Sep. 30, 2011 Pension [Member] Minimum [Member]	Sep. 30, 2011 Pension [Member] Maximum [Member]	Sep. 30, 2013 Pension Plans Excluding Pension Equalization Plan, Defined Benefit [Member]	Sep. 30, 2012 Pension Plans Excluding Pension Equalization Plan, Defined Benefit [Member]	Sep. 30, 2011 Pension Plans Excluding Pension Equalization Plan, Defined Benefit [Member]	Sep. 30, 2013 OPEB [Member]	Sep. 30, 2012 OPEB [Member]	Sep. 30, 2011 OPEB [Member]	Sep. 30, 2013 OPEB [Member] Minimum [Member]	Sep. 30, 2013 OPEB [Member] Maximum [Member]	Sep. 30, 2013 Regulatory Assets [Member] Pension [Member]		Sep. 30, 2012 Regulatory Assets [Member] Pension [Member]		Sep. 30, 2013 Regulatory Assets [Member] OPEB [Member]		Sep. 30, 2012 Regulatory Assets [Member] OPEB [Member]		Sep. 30, 2013 Accumulated Other Comprehensive Income, Location [Member] Pension [Member]	Sep. 30, 2012 Accumulated Other Comprehensive Income, Location [Member] Pension [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income, Location [Member] OPEB [Member]	Sep. 30, 2012 Accumulated Other Comprehensive Income, Location [Member] OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions over the next five years																											$ 3,000,000	$ 5,000,000
Regulatory costs approved			308,000
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year													211,136,000	[1]	171,148,000	[1]								121,027,000	99,066,000
Service cost													6,871,000	[1]	5,375,000	[1]	4,775,000							4,686,000	3,584,000	3,345,000
Interest cost													8,942,000	[1]	8,825,000	[1]	8,378,000							5,148,000	5,133,000	4,845,000
Plan participants' contributions													49,000	[1]	47,000	[1]								32,000	29,000
Amendments													0	[1]	1,083,000	[1]								0	(3,423,000)
Actuarial (gain) loss													(22,288,000)	[1]	30,428,000	[1]								(15,645,000)	18,807,000
Benefits paid, net of retiree subsidies received													(5,884,000)	[1]	(5,770,000)	[1]								(2,477,000)	(2,169,000)
Benefit obligation at end of year													198,826,000	[1]	211,136,000	[1]	171,148,000	[1]						112,771,000	121,027,000	99,066,000
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year													166,664,000	[1]	124,289,000	[1]								41,090,000	31,428,000
Actual return on plan assets													19,323,000	[1]	28,018,000	[1]								5,120,000	6,222,000
Employer contributions													20,083,000	[1]	20,080,000	[1]					20,000,000	20,000,000	4,900,000	5,977,000	5,775,000	6,500,000
Benefits paid, net of plan participants' contributions													(5,834,000)	[1]	(5,723,000)	[1]								(2,632,000)	(2,335,000)
Fair value of plan asset at end of year													200,236,000	[1]	166,664,000	[1]	124,289,000	[1]						49,555,000	41,090,000	31,428,000
Funded status													1,410,000	[1]	(44,472,000)	[1]								(63,216,000)	(79,937,000)
Amounts recognized on Consolidated Balance Sheets, Postemployment benefit liability
Current													(96,000)	[1]	(93,000)	[1]								(100,000)	(120,000)
Non-current		(67,897,000)	(124,196,000)										1,506,000	[1]	(44,379,000)	[1]								(63,116,000)	(79,817,000)
Total													1,410,000	[1]	(44,472,000)	[1]								(63,216,000)	(79,937,000)
Amounts Recognized in Regulatory Assets and Accumulated Other Comprehensive Income [Roll Forward]
Beginning, Regulatory Assets																													80,449,000	[2]	72,355,000		58,799,000	[2]	47,925,000
Beginning, Accumulated Other Comprehensive Income (Loss)																																					25,183,000	22,160,000	1,511,000	3,752,000
Net actuarial loss (gain)																													(17,961,000)		10,896,000		(13,523,000)		16,773,000		(8,826,000)	4,198,000	(3,589,000)	(1,442,000)
Net actuarial (loss)													(7,646,000)		(5,015,000)		(3,946,000)							(3,857,000)	(2,894,000)	(2,612,000)			(5,719,000)		(3,848,000)		(3,743,000)		(2,671,000)		(1,927,000)	(1,166,000)	(114,000)	(223,000)
Prior service credit (cost)													108,000		46,000		48,000							(355,000)	25,000	75,000			(105,000)		1,046,000		301,000		(2,677,000)		(3,000)	(9,000)	54,000	(420,000)
Net transition obligation													0		0		0							26,000	356,000	356,000			0		0		(22,000)		(551,000)		0	0	(4,000)	(156,000)
Net actuarial loss (gain)																													55,559,000		79,239,000		44,140,000		61,406,000		14,412,000	25,165,000	(1,782,000)	1,921,000
Prior service cost (credit)																													1,105,000		1,210,000		(2,339,000)		(2,640,000)		15,000	18,000	(360,000)	(414,000)
Net transition obligation																													0		0		11,000		33,000		0	0	0	4,000
Ending, Regulatory Assets																													56,664,000	[2]	80,449,000	[2]	41,812,000	[2]	58,799,000	[2]
Ending, Accumulated Other Comprehensive Income (Loss)																																					14,427,000	25,183,000	(2,142,000)	1,511,000
Amounts included in regulatory assets and accumulated other comprehensive income
Net actuarial gain, Regulatory Assets													4,348,000											2,607,000
Prior service credit, Regulatory Assets													108,000											11,000
Net transition obligation, Regulatory Assets													0											(303,000)
Total, Regulatory Assets													4,456,000											2,315,000
Net actuarial gain, Accumulated Other Comprehensive Income (Loss)													1,248,000											(107,000)
Prior service credit, Accumulated Other Comprehensive Income (Loss)													3,000											0
Net transition obligation, Accumulated Other Comprehensive Income (Loss)													0											(54,000)
Total, Accumulated Other Comprehensive Income (Loss)													1,251,000											(161,000)
Accumulated benefit obligation in excess of the fair value of plan assets
Projected benefit obligation													198,826,000		211,136,000
Accumulated benefit obligation													176,172,000		186,825,000
Fair value of plan assets													200,236,000		166,664,000
Components of net periodic cost
Service cost													6,871,000	[1]	5,375,000	[1]	4,775,000							4,686,000	3,584,000	3,345,000
Interest cost													8,942,000	[1]	8,825,000	[1]	8,378,000							5,148,000	5,133,000	4,845,000
Expected return on plan assets													(14,825,000)		(12,685,000)		(11,490,000)							(3,653,000)	(2,746,000)	(2,472,000)
Recognized actuarial loss													7,646,000		5,015,000		3,946,000							3,857,000	2,894,000	2,612,000			5,719,000		3,848,000		3,743,000		2,671,000		1,927,000	1,166,000	114,000	223,000
Prior service credit (cost)													108,000		46,000		48,000							(355,000)	25,000	75,000			(105,000)		1,046,000		301,000		(2,677,000)		(3,000)	(9,000)	54,000	(420,000)
Recognized net initial obligation													0		0		0							26,000	356,000	356,000			0		0		(22,000)		(551,000)		0	0	(4,000)	(156,000)
Net periodic cost													8,742,000		6,576,000		5,657,000							9,709,000	9,246,000	8,761,000
Weighted average assumptions used to determine benefit costs
Discount rate													4.30%		5.25%		5.50%							4.30%	5.25%	5.50%
Expected asset return													8.50%		8.25%		8.25%							8.50%	8.25%	8.25%
Compensation increase													3.25%		3.25%				2.50%	3.25%				3.25%	3.25%	3.25%
Weighted average assumptions used to determine obligations
Discount rate													5.15%		4.30%		5.25%							5.15%	4.30%	5.25%
Compensation increase													3.25%		3.25%		3.25%							3.25%	3.25%	3.25%
Information relating to the assumed health care cost trend rate (HCCTR)
HCCTR																								7.30%	7.50%	8.20%
Ultimate HCCTR																								4.80%	4.80%	4.80%
Year ultimate HCCTR reached																								2022	2022	2019
Effect of a 1 percentage point increase in the HCCTR on year-end benefit obligation																								18,008,000	21,278,000	17,193,000
Effect of a 1 percentage point increase in the HCCTR on total service and interest cost																								2,156,000	1,868,000	1,751,000
Effect of a 1 percentage point decrease in the HCCTR on year-end benefit obligation																								(14,629,000)	(17,034,000)	(13,792,000)
Effect of a 1 percentage point decrease in the HCCTR on total service and interest costs																								(1,675,000)	(1,457,000)	(1,367,000)
Desired rate of return before permissible expense after inflation		5.00%
Target allocations
2014 Target Allocation	100.00%			40.00%			20.00%			40.00%
Assets at September 30		100.00%	100.00%		42.00%	39.00%		22.00%	21.00%		36.00%	40.00%
Estimated future benefit payments
2014													6,819,000											3,135,000
2015													7,323,000											3,677,000
2016													7,900,000											4,211,000
2017													8,438,000											4,729,000
2018													9,210,000											5,269,000
2019 - 2023													$ 58,543,000											$ 35,631,000

[1] Includes the Company's PEP.

[2] Balance represents amounts recognized in accordance with ASC 715 and excludes $308,000 associated with a regulatory asset approved by the BPU for fiscal 2012.