Pension Plan and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2022

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
	2022		2021		2022		2021
Service cost	$	9,235	$	9,010	$	1,683	$	1,611
Interest cost	6,329		5,319		1,008		805
Expected return on plan assets	(11,307)		(9,866)		(2,482)		(2,192)
Amortization of prior service cost	242		253		39		49
Recognized net actuarial loss	999		1,924		(228)		(110)
Net periodic benefit cost	$	5,498	$	6,640	$	20	$	163

	Six Months Ended June 30
	Pension Plan				Other Benefits
	2022		2021		2022		2021
Service cost	$	18,470	$	18,020	$	3,366	$	3,222
Interest cost	12,658		10,638		2,016		1,611
Expected return on plan assets	(22,614)		(19,732)		(4,964)		(4,383)
Amortization of prior service cost	484		506		78		97
Recognized net actuarial loss	1,998		3,848		(456)		(220)
Net periodic benefit cost	$	10,996	$	13,280	$	40	$	327