EMPLOYEE BENEFIT PLANS (Tables)

9 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The components of the net periodic cost for pension benefits, including the Company's Pension Equalization Plan, and OPEB costs (principally health care and life insurance) for employees and covered dependents were as follows:

	Pension												OPEB
	Three Months Ended						Nine Months Ended						Three Months Ended						Nine Months Ended
	June 30,						June 30,						June 30,						June 30,
(Thousands)	2018			2017			2018			2017			2018			2017			2018			2017
Service cost	$	2,035		$	2,086		$	6,104		$	6,260		$	1,152		$	1,095		$	3,455		$	3,285
Interest cost	2,623			2,443			7,870			7,328			1,591			1,386			4,773			4,159
Expected return on plan assets	(4,910		)	(4,829		)	(14,729		)	(14,485		)	(1,338		)	(1,192		)	(4,014		)	(3,575		)
Recognized actuarial loss	1,884			2,207			5,653			6,620			1,165			1,093			3,495			3,278
Prior service cost amortization	27			28			80			83			(91		)	(91		)	(273		)	(273		)
Net periodic benefit cost	$	1,659		$	1,935		$	4,978		$	5,806		$	2,479		$	2,291		$	7,436		$	6,874