Retirement plans (Tables)

9 Months Ended

Sep. 30, 2021

Retirement Benefits [Abstract]

Schedule of Benefit Costs

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 Sept. 30,				Nine months ended Sept. 30,
	2021		2020		2021		2020
Service cost-benefits earned during the period	$	1	$	1	$	2	$	5
Interest cost on benefit obligation	3,969		4,868		11,907		14,605
Expected return on plan assets	(8,670)		(7,765)		(26,010)		(23,294)
Amortization of prior service cost	23		23		68		68
Amortization of actuarial loss	1,223		1,541		3,669		4,622
Pension payment timing related charge	946		—		946		—
Income from company-sponsored retirement plans	$	(2,508)	$	(1,332)	$	(9,418)	$	(3,994)