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DERIVATIVE INSTRUMENTS - INCOME STATEMENT RELATED DISCLOSURES (Details) - Derivatives not designated as hedging instruments: - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | $ 56,705 | $ (7,412) | $ (34,175)
Energy Services | Physical commodity contracts | Operating revenues |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | 1,163 | (5,732) | (9,311)
Energy Services | Physical commodity contracts | Natural gas purchases |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | (3,366) | (521) | (197)
Energy Services | Financial commodity contracts | Natural gas purchases |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | 58,949 | (643) | (24,622)
Energy Services | Foreign currency contracts | Natural gas purchases |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | (41) | (283) | (379)
Natural Gas Distribution |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | (1,826) | (1,774) | 11,543
Natural Gas Distribution | Physical commodity contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | 2,077 | 5,926 | 1,232
Natural Gas Distribution | Financial commodity contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | (3,903) | (7,700) | 1,844
Natural Gas Distribution | Interest rate contract |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | 0 | 0 | 8,467
Home Services and Other | Interest rate contract | Interest expense |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of Gain (Loss) Recognized in Income on Derivatives | $ 0 | $ (233) | $ 334

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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