DERIVATIVE INSTRUMENTS - BALANCE SHEET RELATED DISCLOSURES (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Jan. 26, 2018	Sep. 30, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		$ 27,396		$ 30,081
Asset Derivatives, noncurrent		10,560		9,164
Liability Derivatives, current		46,652		46,544
Liability Derivatives, noncurrent		22,982		11,330
Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives		37,956		39,245
Liability Derivatives		69,634		57,874
Interest rate swap
Derivatives, Fair Value [Line Items]
Fixed treasury rate			2.84%
Term loan | Credit Agreement Due August 16, 2019 | Interest rate swap
Derivatives, Fair Value [Line Items]
Long-term debt			$ 100,000
Home Services and Other | Interest rate contract | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		381		0
Liability Derivatives, current		0		0
Natural Gas Distribution | Physical commodity contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		85		151
Liability Derivatives, current		192		72
Natural Gas Distribution | Financial commodity contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		94		0
Liability Derivatives, current		0		1,149
Natural Gas Distribution | Interest rate contract | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current	[1]	0		0
Liability Derivatives, current	[1]	0		8,467
Energy Services | Physical commodity contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		7,667		14,588
Asset Derivatives, noncurrent		3,930		7,127
Liability Derivatives, current		18,158		16,589
Liability Derivatives, noncurrent		11,316		8,710
Energy Services | Financial commodity contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		19,169		15,302
Asset Derivatives, noncurrent		6,630		2,033
Liability Derivatives, current		28,176		20,267
Liability Derivatives, noncurrent		11,548		2,620
Energy Services | Foreign currency contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Asset Derivatives, current		0		40
Asset Derivatives, noncurrent		0		4
Liability Derivatives, current		126		0
Liability Derivatives, noncurrent		$ 118		$ 0

[1] Includes treasury lock which was settled in March 2018. See Note 8. Debt for more information.