EMPLOYEE BENEFIT PLANS (Tables)

9 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Components of Net Periodic Cost

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)	2023		2022		2023		2022		2023		2022		2023		2022
Service cost	$	1,350	$	2,073	$	4,051	$	6,219	$	618	$	1,077	$	1,854	$	3,229
Interest cost	3,794		2,408		11,381		7,224		2,286		1,588		6,859		4,766
Expected return on plan assets	(4,993)		(5,319)		(14,979)		(15,956)		(1,680)		(1,893)		(5,041)		(5,681)
Recognized actuarial loss	75		2,186		225		6,558		—		1,421		—		4,263
Prior service cost (credit) amortization	25		25		76		76		—		(35)		—		(107)
Net periodic benefit cost	$	251	$	1,373	$	754	$	4,121	$	1,224	$	2,158	$	3,672	$	6,470