EMPLOYEE BENEFIT PLANS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Components of net periodic cost
Discretionary contribution			$ 0	$ 0
Pension
Components of net periodic cost
Service cost	$ 1,845,000	$ 2,035,000	5,536,000	6,104,000
Interest cost	3,043,000	2,623,000	9,129,000	7,870,000
Expected return on plan assets	(4,763,000)	(4,910,000)	(14,290,000)	(14,729,000)
Recognized actuarial loss	1,442,000	1,884,000	4,324,000	5,653,000
Prior service cost amortization	25,000	27,000	76,000	80,000
Net periodic benefit cost	1,592,000	1,659,000	4,775,000	4,978,000
OPEB
Components of net periodic cost
Service cost	1,101,000	1,152,000	3,303,000	3,455,000
Interest cost	2,081,000	1,591,000	6,243,000	4,773,000
Expected return on plan assets	(1,379,000)	(1,338,000)	(4,137,000)	(4,014,000)
Recognized actuarial loss	1,617,000	1,165,000	4,850,000	3,495,000
Prior service cost amortization	(91,000)	(91,000)	(273,000)	(273,000)
Net periodic benefit cost	$ 3,329,000	$ 2,479,000	$ 9,986,000	$ 7,436,000