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DERIVATIVE INSTRUMENTS - INCOME STATEMENT RELATED DISCLOSURES (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands | 3 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | $ (10,389) | $ (47,532)
Interest rate contracts | Interest Expense | Home Services and Other |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | (123) | 0
Energy Services | Physical commodity contracts | Operating revenues |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | (1,532) | 1,210
Energy Services | Physical commodity contracts | Gas purchases |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | (5,432) | (22,697)
Energy Services | Financial commodity contracts | Gas purchases |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | (2,956) | (25,997)
Energy Services | Foreign currency contracts | Gas purchases |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | (346) | (48)
Natural Gas Distribution |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | 7,373 | (15,851)
Natural Gas Distribution | Physical commodity contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | 2,977 | (2,976)
Natural Gas Distribution | Financial commodity contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | 4,396 | (8,808)
Natural Gas Distribution | Interest rate contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of (losses) gains recognized in income on derivatives | $ 0 | $ (4,067)

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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=109980867&loc=SL5618551-113959 + Details
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