REGULATION, REGULATORY FILINGS (Details)									1 Months Ended								4 Months Ended	12 Months Ended
	Oct. 01, 2016 USD ($)	Sep. 16, 2016 USD ($)	Jul. 20, 2016 USD ($)	Jun. 29, 2016 USD ($)	Dec. 24, 2015	Nov. 13, 2015 USD ($)	Nov. 01, 2015	Oct. 01, 2015	Oct. 31, 2015	Jul. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Oct. 31, 2014	Jul. 31, 2014 USD ($) project	Jun. 30, 2014 USD ($)	Oct. 31, 2012 USD ($)	Jun. 30, 2012 USD ($)	Feb. 29, 2016 USD ($)	Sep. 30, 2016 USD ($) station	Sep. 30, 2010 USD ($)	Sep. 30, 2015 USD ($)
Public Utilities, General Disclosures [Line Items]
Requested base rate increase, amount			$ 112,900,000			$ 147,600,000
Composite rate of depreciation	2.34%
Recovery period																		7 years
Tax charge resulting from a change in deductibility of federal subsidies																			$ 2,900,000
Regulatory assets, noncurrent																		$ 441,294,000		$ 410,155,000
Estimated annual bill credits		$ 48,000,000															$ 61,600,000
Average residential heating customer, percent of increase (decrease)		(10.60%)
Number of NGV stations opened to the public | station																		3
Other Regulatory Asset
Public Utilities, General Disclosures [Line Items]
Regulatory asset, maximum amount to be recorded annually																		$ 700,000
Regulatory asset, expense benchmark																		1,400,000
Regulatory assets, threshold of recording regulatory liability when net liability exceeds amount																		1,000,000
Other Regulatory Asset, PIM
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent																		4,400,000
SAFE Program
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU															$ 130,000,000
Capital investments approved by the BPU, period															4 years
SAVEGREEN
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU																		219,300,000
Grants, rebates and loans provided to customers																		136,600,000
Increase in regulatory funding obligations																		$ 20,000,000
Additional investments										$ 75,200,000
SAVEGREEN | Minimum
Public Utilities, General Disclosures [Line Items]
Return on equity																		9.75%
Public utilities, approved equity capital structure, percentage																		6.69%
SAVEGREEN | Minimum | June 2012 SAVEGREEN Filing
Public Utilities, General Disclosures [Line Items]
Program recovery term																		2 years
SAVEGREEN | Maximum
Public Utilities, General Disclosures [Line Items]
Return on equity																		10.30%
Public utilities, approved equity capital structure, percentage																		7.76%
SAVEGREEN | Maximum | June 2012 SAVEGREEN Filing
Public Utilities, General Disclosures [Line Items]
Program recovery term																		10 years
NJ RISE Program
Public Utilities, General Disclosures [Line Items]
Return on equity							9.75%
Public utilities, approved equity capital structure, percentage							6.74%
Program recovery term													5 years
Requested rate increase (decrease), percentage							0.07%
Number of capital investment projects | project													6
Originally filed petition for capital investments to Board of Public Utilities													$ 102,500,000
CIP
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage									0.08%			(4.30%)
BGSS
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage												(5.00%)
SBC | September 2014 SBC Filing
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage											(3.30%)
Approved rate, amount														$ 8,500,000
SBC | December 2015 SBC Filing
Public Utilities, General Disclosures [Line Items]
Approved rate, amount				$ 9,400,000
New Jersey Clean Energy Program | September 2014 SBC Filing
Public Utilities, General Disclosures [Line Items]
Approved rate, amount											$ 16,300,000
USF
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage								(0.60%)
NJCEP
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage					(0.80%)
Compressed Natural Gas Vehicle Refueling Stations
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU																$ 10,000,000
SRL-Southern Reliability Link | Minimum
Public Utilities, General Disclosures [Line Items]
Estimated cost of the SRL																		$ 175,000,000
SRL-Southern Reliability Link | Maximum
Public Utilities, General Disclosures [Line Items]
Estimated cost of the SRL																		$ 180,000,000
Subsequent Event
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease), amount	$ 45,000,000
Return on equity	9.75%
Public utilities, approved equity capital structure, percentage	52.50%
Composite rate of depreciation	2.40%
Recovery of expenditures, approved rolling period	7 years
Subsequent Event | SAFE Program
Public Utilities, General Disclosures [Line Items]
Program recovery term	5 years
Capital investments approved by the BPU	$ 200,000,000
Capital Investments to be Recovered Approved By The Board Of Public Utilities	$ 157,500,000
Subsequent Event | NJ RISE Program
Public Utilities, General Disclosures [Line Items]
Public utilities, approved equity capital structure, percentage	6.90%
Program recovery term	7 years
Subsequent Event | CIP
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage	8.20%
Subsequent Event | BGSS
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage	(5.50%)
Subsequent Event | USF
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage	0.20%
Subsequent Event | LNG-Liquefied Natural Gas
Public Utilities, General Disclosures [Line Items]
Capital Investments to be Recovered Approved By The Board Of Public Utilities	$ 36,500,000