Retirement plans (Tables)

3 Months Ended

Mar. 31, 2023

Retirement Benefits [Abstract]

Schedule of Benefit Costs (Income)

Pension costs (income), which primarily include costs for the qualified TRP and the non-qualified SERP, are presented in the following table (in thousands):

	Quarter ended Mar. 31,
	2023		2022
Interest cost on benefit obligation	$	6,150	$	4,300
Expected return on plan assets	(5,225)		(4,900)
Amortization of prior service credit	(125)		(125)
Amortization of actuarial loss	1,575		1,100
Expense from company-sponsored retirement plans	$	2,375	$	375