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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - DEMAND FEES (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Demand fees	$ 206.6	$ 218.8	$ 211.1
Energy Services
Demand fees	126.4	141.0	130.6
Natural Gas Distribution
Demand fees	$ 80.2	$ 77.8	$ 80.5
Minimum
Storage and pipeline capacity, contract term	1 year
Maximum
Storage and pipeline capacity, contract term	10 years

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- Definition

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- Definition

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