EMPLOYEE BENEFIT PLANS (Tables)

6 Months Ended

Mar. 31, 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						Six Months Ended						Three Months Ended						Six Months Ended
	March 31,						March 31,						March 31,						March 31,
(Thousands)	2018			2017			2018			2017			2018			2017			2018			2017
Service cost	$	2,034		$	2,087		$	4,069		$	4,174		$	1,151		$	1,095		$	2,303		$	2,190
Interest cost	2,624			2,442			5,247			4,885			1,591			1,387			3,182			2,773
Expected return on plan assets	(4,909		)	(4,828		)	(9,819		)	(9,656		)	(1,338		)	(1,191		)	(2,676		)	(2,383		)
Recognized actuarial loss	1,885			2,206			3,769			4,413			1,165			1,092			2,330			2,185
Prior service cost amortization	26			28			53			55			(91		)	(91		)	(182		)	(182		)
Net periodic benefit cost	$	1,660		$	1,935		$	3,319		$	3,871		$	2,478		$	2,292		$	4,957		$	4,583