DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands		Mar. 31, 2019		Sep. 30, 2018
Energy Services
Derivative assets:
Amounts Presented in Balance Sheets	[1]	$ 35,200		$ 37,396
Offsetting Derivative Instruments	[2]	(26,888)		(22,719)
Financial Collateral Received/Pledged	[3]	(2,589)		(200)
Net Amounts	[4]	5,723		14,477
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	72,890		69,442
Offsetting Derivative Instruments	[2]	(26,888)		(22,719)
Financial Collateral Received/Pledged	[3]	(9,032)		(20,949)
Net Amounts	[4]	36,970		25,774
Energy Services | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	5,881		11,597
Offsetting Derivative Instruments	[2]	(1,428)		(3,944)
Financial Collateral Received/Pledged	[3]	(200)		(200)
Net Amounts	[4]	4,253		7,453
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	35,658		29,474
Offsetting Derivative Instruments	[2]	(1,428)		(3,944)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	34,230		25,530
Energy Services | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	29,317		25,799
Offsetting Derivative Instruments	[2]	(25,458)		(18,775)
Financial Collateral Received/Pledged	[3]	(2,389)		0
Net Amounts	[4]	1,470		7,024
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	36,878		39,724
Offsetting Derivative Instruments	[2]	(25,458)		(18,775)
Financial Collateral Received/Pledged	[3]	(9,032)		(20,949)
Net Amounts	[4]	2,388		0
Energy Services | Foreign currency contracts
Derivative assets:
Amounts Presented in Balance Sheets		2
Offsetting Derivative Instruments		(2)
Financial Collateral Received/Pledged		0
Net Amounts		0
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	354		244
Offsetting Derivative Instruments	[2]	(2)		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	352		244
Natural Gas Distribution
Derivative assets:
Amounts Presented in Balance Sheets		669	[1]	179
Offsetting Derivative Instruments		(7)	[2]	(3)
Financial Collateral Received/Pledged		(571)	[3]	(94)
Net Amounts		91	[4]	82
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	56		192
Offsetting Derivative Instruments	[2]	(7)		(3)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	49		189
Natural Gas Distribution | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets		91	[1]	85
Offsetting Derivative Instruments		0	[2]	(3)
Financial Collateral Received/Pledged		0	[3]	0
Net Amounts		91	[4]	82
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	49		192
Offsetting Derivative Instruments	[2]	0		(3)
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	49		189
Natural Gas Distribution | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets		578	[1]	94
Offsetting Derivative Instruments		(7)	[2]	0
Financial Collateral Received/Pledged		(571)	[3]	(94)
Net Amounts		0	[4]	0
Derivative liabilities:
Amounts Presented in Balance Sheets	[1]	7
Offsetting Derivative Instruments	[2]	(7)
Financial Collateral Received/Pledged	[3]	0
Net Amounts	[4]	0
Home Services and Other
Derivative assets:
Amounts Presented in Balance Sheets	[1]	120		381
Offsetting Derivative Instruments	[2]	0		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	120		381
Home Services and Other | Interest rate contracts
Derivative assets:
Amounts Presented in Balance Sheets	[1]	120		381
Offsetting Derivative Instruments	[2]	0		0
Financial Collateral Received/Pledged	[3]	0		0
Net Amounts	[4]	$ 120		$ 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.