Employee Benefit Plans: (Tables)

9 Months Ended

Sep. 30, 2022

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, 2022 and 2021 were as follows:


	For The Three Months Ended September 30,
	Pension Benefits				Other Postretirement Benefits				SERP
(dollars in thousands)	2022		2021		2022		2021		2022		2021
Components of Net Periodic Benefits Cost:
Service cost	$	1,411	$	1,487	$	30	$	31	$	298	$	348
Interest cost	1,850		1,700		13		22		256		229
Expected return on plan assets	(3,291)		(3,137)		(147)		(134)		—		—
Amortization of prior service cost	109		109		—		—		—		—
Amortization of actuarial (gain) loss	—		876		(478)		(488)		145		419
Net periodic benefits costs under accounting standards	79		1,035		(582)		(569)		699		996
Regulatory adjustment - deferred	—		(254)		—		—		—		—
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	$	79	$	781	$	(582)	$	(569)	$	699	$	996


	For The Nine Months Ended September 30,
	Pension Benefits				Other Postretirement Benefits				SERP
(dollars in thousands)	2022		2021		2022		2021		2022		2021
Components of Net Periodic Benefits Cost:
Service cost	$	4,233	$	4,737	$	96	$	111	$	894	$	1,044
Interest cost	5,550		5,124		45		84		768		687
Expected return on plan assets	(9,873)		(9,405)		(441)		(402)		—		—
Amortization of prior service cost	327		327		—		—		—		—
Amortization of actuarial (gain) loss	—		2,862		(1,302)		(1,062)		435		1,257
Net periodic benefits costs under accounting standards	237		3,645		(1,602)		(1,269)		2,097		2,988
Regulatory adjustment - deferred	—		(956)		—		—		—		—
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	$	237	$	2,689	$	(1,602)	$	(1,269)	$	2,097	$	2,988