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REGULATION, REGULATORY FILINGS (Details) |  |  |  |  |  | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 27, 2015 USD ($) | Oct. 15, 2015 | Jul. 22, 2015 USD ($) | Apr. 23, 2014 USD ($) | Sep. 03, 2013 USD ($) project | Sep. 30, 2014 USD ($) | Jul. 31, 2013 USD ($) | Oct. 31, 2012 USD ($) | Sep. 30, 2015 USD ($) station | Sep. 30, 2014 USD ($) | Sep. 30, 2013 | Jun. 05, 2015 petition | Apr. 02, 2015 petition
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery period |  |  |  |  |  |  |  |  | 7 years |  |  |  |
Tax charge resulting from a change in deductibility of federal subsidies |  |  |  |  |  |  |  |  | $ (2,900,000) |  |  |  |
Regulatory assets, noncurrent |  |  |  |  |  | $ 377,575,000 |  |  | $ 410,155,000 | $ 377,575,000 |  |  |
Regulatory liability, amortization period |  |  |  |  |  |  |  |  | 48 years |  |  |  |
Number of NGV stations opened to the public | station |  |  |  |  |  |  |  |  | 2 |  |  |  |
Debt instrument, term |  |  |  | 3 years |  |  |  |  |  |  |  |  |
Maximum issuance amount |  |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |
Maximum maturity period |  |  |  | 30 years |  |  |  |  |  |  |  |  |
Credit facility, renewal period |  |  |  | 5 years |  |  |  |  |  |  |  |  |
SAVEGREEN [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Capital investments approved by the BPU |  |  |  |  |  |  |  |  | $ 219,300,000 |  |  |  |
Grants, rebates and loans provided to customers |  |  |  |  |  |  |  |  | 117,500,000 |  |  |  |
Increase in regulatory funding obligations |  |  |  |  |  |  |  |  | $ 20,000,000 |  |  |  |
Additional investments |  |  | $ 75,200,000 |  |  |  |  |  |  |  |  |  |
BGSS [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  | (5.00%) |  |  |
Interim rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  |  | (6.00%) |  |
BGSS [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated annual bill credits | $ 76,000,000 |  |  |  |  |  |  |  |  |  |  |  |
(Decrease) in average residential heat customer's bill | (17.00%) |  |  |  |  |  |  |  |  |  |  |  |
CIP [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  | (4.30%) | (1.00%) |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  | 0.08% |  |  |  |
AIP I and AIP II [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Total investment |  |  |  |  |  |  |  |  | $ 148,700,000 |  |  |  |
Approved rate, amount |  |  |  |  |  |  |  |  | $ 15,300,000 |  |  |  |
Return on equity |  |  |  |  |  |  |  |  | 10.30% |  |  |  |
AIP I [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Public utilities, approved equity capital structure, percentage |  |  |  |  |  |  |  |  | 7.76% |  |  |  |
AIP II [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Public utilities, approved equity capital structure, percentage |  |  |  |  |  |  |  |  | 7.12% |  |  |  |
SAFE Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Capital investments approved by the BPU |  |  |  |  |  |  |  | $ 130,000,000 |  |  |  |  |
Capital investments approved by the BPU, period |  |  |  |  |  |  |  | 4 years |  |  |  |  |
Compressed Natural Gas Vehicle Refueling Stations [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Capital investments approved by the BPU |  |  |  |  |  |  |  |  | $ 10,000,000 |  |  |  |
NJ RISE Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Program recovery term |  |  |  |  | 5 years |  |  |  |  |  |  |  |
Public utilities, approved equity capital structure, percentage |  |  |  |  |  |  |  |  | 6.74% |  |  |  |
Return on equity |  |  |  |  |  |  |  |  | 9.75% |  |  |  |
Number of capital investment projects | project |  |  |  |  | 6 |  |  |  |  |  |  |  |
Originally filed petition for capital investments to Board of Public Utilities |  |  |  |  | $ 102,500,000 |  |  |  |  |  |  |  |
NJ RISE Program [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  | 0.07% |  |  |  |  |  |  |  |  |  |  |
SBC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  |  | (0.20%) |  |
New Jersey Clean Energy Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in regulatory funding obligations |  |  |  |  |  |  |  |  |  | $ 15,600,000 |  |  |
USF [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  | (0.60%) | 0.40% |  |  |
Red Oak [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Capital investments approved by the BPU |  |  |  |  |  |  |  |  | $ 1,400,000 |  |  |  |
SRL-Southern Reliability Link [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Number of petitions with the BPU | petition |  |  |  |  |  |  |  |  |  |  |  | 2 | 2
Other Regulatory Asset [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |
Regulatory assets, noncurrent |  |  |  |  |  | 6,797,000 |  |  | 5,537,000 | $ 6,797,000 |  |  |
Other Regulatory Asset, PIM [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets, noncurrent |  |  |  |  |  |  |  |  | 3,700,000 |  |  |  |
Deferred Superstorm Sandy Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets, noncurrent |  |  |  |  |  | 15,207,000 |  |  | $ 15,201,000 | $ 15,207,000 |  |  |
July 2013 SBC Filing [Member] | SBC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Approved rate, amount |  |  |  |  |  |  | $ 18,700,000 |  |  |  |  |  |
July 2013 SBC Filing [Member] | New Jersey Clean Energy Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  |  | 1.90% |  |
September 2014 SBC Filing [Member] | SBC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percentage |  |  |  |  |  |  |  |  |  | (3.30%) |  |  |
Requested rate, amount |  |  |  |  |  | $ 8,500,000 |  |  |  |  |  |  |
September 2014 SBC Filing [Member] | New Jersey Clean Energy Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate, amount |  |  |  |  |  |  |  |  |  | $ 16,300,000 |  |  |
Minimum [Member] | SAVEGREEN [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Public utilities, approved equity capital structure, percentage |  |  |  |  |  |  |  |  | 6.69% |  |  |  |
Return on equity |  |  |  |  |  |  |  |  | 9.75% |  |  |  |
Minimum [Member] | SRL-Southern Reliability Link [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated cost of the SRL |  |  |  |  |  |  |  |  | $ 175,000,000 |  |  |  |
Minimum [Member] | June 2012 SAVEGREEN Filing [Member] | SAVEGREEN [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Program recovery term |  |  |  |  |  |  |  |  | 2 years |  |  |  |
Maximum [Member] | SAVEGREEN [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Public utilities, approved equity capital structure, percentage |  |  |  |  |  |  |  |  | 7.76% |  |  |  |
Return on equity |  |  |  |  |  |  |  |  | 10.30% |  |  |  |
Maximum [Member] | SRL-Southern Reliability Link [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated cost of the SRL |  |  |  |  |  |  |  |  | $ 180,000,000 |  |  |  |
Maximum [Member] | June 2012 SAVEGREEN Filing [Member] | SAVEGREEN [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Program recovery term |  |  |  |  |  |  |  |  | 10 years |  |  |  |

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