DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands		Jun. 30, 2019		Sep. 30, 2018
Energy Services
Derivative assets:
Amounts Presented in Balance Sheets	[1]	$ 42,522		$ 37,396
Offsetting Derivative Instruments	[2]	(31,103)		(22,719)
Financial Collateral Received/Pledged	[3]	(814)		(200)
Net Amounts	[4]	10,605		14,477
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	65,519		69,442
Offsetting Derivative Instruments	[2]	(31,103)		(22,719)
Financial Collateral Received/Pledged	[3]	(654)		(20,949)
Net Amounts	[4]	33,762		25,774
Energy Services | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	11,000		11,597
Offsetting Derivative Instruments	[2]	(4,187)		(3,944)
Financial Collateral Received/Pledged	[3]	(200)		(200)
Net Amounts	[4]	6,613		7,453
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	37,056		29,474
Offsetting Derivative Instruments	[2]	(4,187)		(3,944)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	32,869		25,530
Energy Services | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	31,512		25,799
Offsetting Derivative Instruments	[2]	(26,906)		(18,775)
Financial Collateral Received/Pledged	[3]	(614)		0
Net Amounts	[4]	3,992		7,024
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	28,199		39,724
Offsetting Derivative Instruments	[2]	(26,906)		(18,775)
Financial Collateral Received/Pledged	[3]	(654)		(20,949)
Net Amounts	[4]	639		0
Energy Services | Foreign currency contracts
Derivative assets:
Amounts Presented in Balance Sheets		10
Offsetting Derivative Instruments		(10)
Financial Collateral Received/Pledged		0
Net Amounts		0
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	264		244
Offsetting Derivative Instruments	[2]	(10)		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	254		244
Natural Gas Distribution
Derivative assets:
Amounts Presented in Balance Sheets		271	[1]	179
Offsetting Derivative Instruments		(19)	[2]	(3)
Financial Collateral Received/Pledged		0	[3]	(94)
Net Amounts		252	[4]	82
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	81		192
Offsetting Derivative Instruments	[2]	(19)		(3)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	62		189
Natural Gas Distribution | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets		55	[1]	85
Offsetting Derivative Instruments		0	[2]	(3)
Financial Collateral Received/Pledged		0	[3]	0
Net Amounts		55	[4]	82
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	62		192
Offsetting Derivative Instruments	[2]	0		(3)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	62		189
Natural Gas Distribution | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets		216	[1]	94
Offsetting Derivative Instruments		(19)	[2]	0
Financial Collateral Received/Pledged		0	[3]	(94)
Net Amounts		197	[4]	0
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	19
Offsetting Derivative Instruments	[2]	(19)
Financial Collateral Received/Pledged	[3]	0
Net Amounts	[4]	0
Home Services and Other
Derivative assets:
Amounts Presented in Balance Sheets	[1]	20		381
Offsetting Derivative Instruments	[2]	0		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	20		381
Home Services and Other | Interest rate contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	20		381
Offsetting Derivative Instruments	[2]	0		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	$ 20		$ 381

[1] Derivative assets and liabilities are presented on a gross basis on the balance sheet as the Company does not elect balance sheet offsetting under ASC 210-20.

[2] Includes transactions with NAESB netting election, transactions held by FCMs with net margining and transactions with ISDA netting.

[3] Financial collateral includes cash balances at FCMs as well as cash received from or pledged to other counterparties.

[4] Net amounts represent presentation of derivative assets and liabilities if the Company were to elect balance sheet offsetting under ASC 210-20.