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INCOME TAXES - INCOME TAX CARRYFORWARDS (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016
Operating Loss Carryforwards [Line Items] |  |
Tax benefit associated with the loss carryforwards | $ 23,597 | $ 18,113
Tax credit carryforward, expiration period | 20 years |
Deferred tax asset, loss carryforwards | $ 52,100 |
Natural Gas Distribution |  |
Operating Loss Carryforwards [Line Items] |  |
Tax credit carryforward | 2,300 | 2,500
Clean Energy Ventures |  |
Operating Loss Carryforwards [Line Items] |  |
Tax credit carryforward | 109,300 | 74,000
Domestic Tax Authority |  |
Operating Loss Carryforwards [Line Items] |  |
Net operating losses | 125,300 | 78,700
Income taxes receivable | 15,400 |
State and Local Jurisdiction |  |
Operating Loss Carryforwards [Line Items] |  |
Net operating losses | 471,700 | 310,600
Deferred tax asset, loss carryforwards | 161,397 |
State and Local Jurisdiction | Fiscal years 2018 - 2022 |  |
Operating Loss Carryforwards [Line Items] |  |
Deferred tax asset, loss carryforwards | 313 |
State and Local Jurisdiction | Fiscal years 2023 - 2027 |  |
Operating Loss Carryforwards [Line Items] |  |
Deferred tax asset, loss carryforwards | 1,051 |
State and Local Jurisdiction | Fiscal years 2028 - 2032 |  |
Operating Loss Carryforwards [Line Items] |  |
Deferred tax asset, loss carryforwards | 796 |
State and Local Jurisdiction | Fiscal years 2033 - 2037 |  |
Operating Loss Carryforwards [Line Items] |  |
Deferred tax asset, loss carryforwards | $ 159,237 |
Minimum | State and Local Jurisdiction |  |
Operating Loss Carryforwards [Line Items] |  |
Net operating losses, life | 7 years |
Maximum | State and Local Jurisdiction |  |
Operating Loss Carryforwards [Line Items] |  |
Net operating losses, life | 20 years |
MONTANA |  |
Operating Loss Carryforwards [Line Items] |  |
Valuation allowance | $ 1,000 |
NEW JERSEY |  |
Operating Loss Carryforwards [Line Items] |  |
Valuation allowance |  | $ 262

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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28680-109314 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319 + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28680-109314 + Details
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