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ACQUISITION (Details) $ in Thousands |  |  | 9 Months Ended
--- | --- | --- | ---
Nov. 07, 2017 USD ($) | Oct. 27, 2017 USD ($) mi | Jun. 30, 2018 USD ($) | Jun. 30, 2017 USD ($)
Business Acquisition [Line Items] |  |  |  |
Payment made at closing |  |  | $ 10,000 | $ 0
Talen Generation, LLC | Talen's Membership Interests In IEC |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Pipeline length owned | mi |  | 84 |  |
Natural gas transportation capacity agreement, period |  | 10 years |  |
Adelphia | Talen Generation, LLC | Talen's Membership Interests In IEC |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Consideration to be transferred |  | $ 166,000 |  |
Contingent consideration arrangements, additional consideration |  | $ 23,000 |  |
Payment made at closing | $ 10,000 |  |  |

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- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
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- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
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