FAIR VALUE - HIERARCHY (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 51,836	$ 39,245
Liabilities	122,547	57,874
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	55,995	65,752
Other	1,106	1,202
Total assets at fair value	108,937	106,199
Total liabilities at fair value	122,547	57,874
Fair Value, Measurements, Recurring | Physical commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	16,535	21,866
Liabilities	38,840	25,371
Fair Value, Measurements, Recurring | Financial commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	35,265	17,335
Liabilities	71,143	24,036
Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	36	44
Liabilities	30
Fair Value, Measurements, Recurring | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	12,534	8,467
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	55,995	65,752
Other	1,106	1,202
Total assets at fair value	92,366	84,289
Total liabilities at fair value	71,143	24,036
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1) | Physical commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1) | Financial commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	35,265	17,335
Liabilities	71,143	24,036
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1) | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1) | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	0	0
Other	0	0
Total assets at fair value	16,571	21,910
Total liabilities at fair value	51,404	33,838
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Physical commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	16,535	21,866
Liabilities	38,840	25,371
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Financial commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0
Liabilities	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	36	44
Liabilities	30
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	12,534	8,467
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	0	0
Other	0	0
Total assets at fair value	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Physical commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Financial commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0
Liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets, (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 4	$ 112