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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - SALE-LEASEBACKS (Details) $ in Thousands | 1 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2017 USD ($) asset | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($)
Sale Leaseback Transaction [Line Items] |  |  |  |
Proceeds from sale-leaseback transaction |  | $ 9,587 | $ 7,107 | $ 7,216
Proceeds from sale-leaseback transaction - solar |  | 32,901 | 0 | 0
NJNG |  |  |  |
Sale Leaseback Transaction [Line Items] |  |  |  |
Proceeds from sale-leaseback transaction |  | $ 9,587 | $ 7,100 | $ 7,200
Minimum | NJNG |  |  |  |
Sale Leaseback Transaction [Line Items] |  |  |  |
Term of lease |  | 7 years |  |
Maximum | NJNG |  |  |  |
Sale Leaseback Transaction [Line Items] |  |  |  |
Term of lease |  | 11 years |  |
Clean Energy Ventures |  |  |  |
Sale Leaseback Transaction [Line Items] |  |  |  |
Term of lease | 7 years |  |  |
Proceeds from sale-leaseback transaction - solar | $ 32,901 |  |  |
Number of commercial solar assets sold | asset | 2 |  |  |

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- Definition Amount of cash inflow after closing and debt issuance costs received by a seller-lessee in a sale-leaseback recognized in financing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 51 -URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51840-112757 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51831-112757 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51843-112757 + Details
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