Interim Pension and Other Postretirement Benefit Plan Information

3 Months Ended

Dec. 31, 2023

Retirement Benefits, Description [Abstract]

Interim Pension and Other Postretirement Benefit Plan Information

Interim Pension and Other Postretirement Benefit Plan Information

The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three months ended December 31, 2023 and 2022 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense.

In the first quarter of fiscal 2024, due to the retirement of an executive, we recognized a settlement charge of $0.8 million associated with our Supplemental Executive Retirement Plan and revalued the net periodic pension cost for the remainder of fiscal 2024. The revaluation of the net periodic pension cost for our Supplemental Executive Retirement Plan resulted in a

decrease in the discount rate, effective November 30, 2023, to 5.82% from 6.17%, which will decrease our net periodic pension cost by approximately $0.4 million for the remainder of the fiscal year.

	Three Months Ended December 31
	Pension Benefits				Other Benefits
	2023		2022		2023		2022
	(In thousands)
Components of net periodic pension cost:
Service cost	$	2,389	$	2,908	$	1,507	$	1,546
Interest cost (1)	7,497		7,325		3,509		3,478
Expected return on assets (1)	(7,202)		(7,278)		(3,128)		(2,804)
Amortization of prior service cost (credit) (1)	—		(30)		(3,260)		(3,285)
Amortization of actuarial (gain) loss (1)	118		164		(2,718)		(1,863)
Settlements (1)	776		—		—		—
Net periodic pension cost	$	3,578	$	3,089	$	(4,090)	$	(2,928)

(1)    The components of net periodic cost other than the service cost component are included in the line item other non-operating expense in the condensed consolidated statements of comprehensive income or are capitalized on the condensed consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2023.