Employee Benefit Plans: (Tables)

9 Months Ended

Sep. 30, 2023

Schedule of components of net periodic benefit costs, before allocation to the overhead pool, for Registrant's pension plan, postretirement plan, and SERP

The components of net periodic benefit costs for Registrant’s pension plan, postretirement medical benefit plan and SERP for the three and nine months ended September 30, 2023 and 2022 were as follows:


	For The Three Months Ended September 30,
	Pension Benefits				Other Postretirement Benefits				SERP
(dollars in thousands)	2023		2022		2023		2022		2023		2022
Components of Net Periodic Benefits Cost:
Service cost	$	705	$	1,411	$	33	$	30	$	312	$	298
Interest cost	2,581		1,850		26		13		411		256
Expected return on plan assets	(2,617)		(3,291)		(119)		(147)		—		—
Amortization of prior service cost	110		109		—		—		—		—
Amortization of actuarial (gain) loss	—		—		(242)		(478)		(8)		145
Net periodic benefits costs under accounting standards	779		79		(302)		(582)		715		699
Regulatory adjustments - deferred	(27)		—		—		—		—		—
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	$	752	$	79	$	(302)	$	(582)	$	715	$	699


	For The Nine Months Ended September 30,
	Pension Benefits				Other Postretirement Benefits				SERP
(dollars in thousands)	2023		2022		2023		2022		2023		2022
Components of Net Periodic Benefits Cost:
Service cost	$	2,397	$	4,233	$	99	$	96	$	936	$	894
Interest cost	7,607		5,550		77		45		1,233		768
Expected return on plan assets	(7,863)		(9,873)		(358)		(441)		—		—
Amortization of prior service cost	326		327		—		—		—		—
Amortization of actuarial (gain) loss	—		—		(724)		(1,302)		(24)		435
Net periodic benefits costs under accounting standards	2,467		237		(906)		(1,602)		2,145		2,097
Regulatory adjustments - deferred	(211)		—		—		—		—		—
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	$	2,256	$	237	$	(906)	$	(1,602)	$	2,145	$	2,097