Retirement plans (Tables)

9 Months Ended

Sep. 30, 2020

Retirement Benefits [Abstract]

Benefit Costs

Pension costs, 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,
	2020		2019		2020		2019
Service cost-benefits earned during the period	$	1	$	2	$	5	$	6
Interest cost on benefit obligation	4,868		5,761		14,605		17,284
Expected return on plan assets	(7,765)		(6,580)		(23,294)		(19,740)
Amortization of prior service cost	23		23		68		68
Amortization of actuarial loss	1,541		1,521		4,622		4,562
Pension payment timing related charge	—		—		—		686
(Gains from) expense for company-sponsored retirement plans	$	(1,332)	$	727	$	(3,994)	$	2,866