Pension Plan and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Schedule of components of net periodic benefit costs for the pension plans and other postretirement benefits

The following tables list components of net periodic benefit costs for the pension plans and other postretirement benefits. The data listed under “pension plan” includes the qualified pension plan and the non-qualified supplemental executive retirement plan. The data listed under “other benefits” is for all other postretirement benefits.

	Three Months Ended June 30
	Pension Plan				Other Benefits
	2023		2022		2023		2022
Service cost	$	6,046	$	9,235	$	1,126	$	1,683
Interest cost	8,746		6,329		1,297		1,008
Expected return on plan assets	(13,421)		(11,307)		(2,636)		(2,482)
Amortization of prior service cost	131		242		39		39
Recognized net actuarial (gain) loss	(637)		999		(581)		(228)
Net periodic benefit cost (benefit)	$	865	$	5,498	$	(755)	$	20

	Six Months Ended June 30
	Pension Plan				Other Benefits
	2023		2022		2023		2022
Service cost	$	12,092	$	18,470	$	2,252	$	3,366
Interest cost	17,492		12,658		2,595		2,016
Expected return on plan assets	(26,842)		(22,614)		(5,271)		(4,964)
Amortization of prior service cost	262		484		77		78
Recognized net actuarial loss	(1,274)		1,998		(1,163)		(456)
Net periodic benefit cost	$	1,730	$	10,996	$	(1,510)	$	40