Pensions and other postretirement benefit plans (Tables)

3 Months Ended

Mar. 31, 2022

Retirement Benefits [Abstract]

Summary of retirement plan costs

Retirement plan costs include the following components:

	Pension benefits				Postretirement benefits
	Three months ended March 31,				Three months ended March 31,
In thousands	2022		2021		2022		2021
Operating expenses:
Service cost - benefits earned during the period	$	475	$	511	$	15	$	31
Non-operating expenses:
Interest cost on benefit obligation	18,649		17,031		451		501
Expected return on plan assets	(37,281)		(41,430)		—		—
Amortization of actuarial loss (gain)	20		35		(52)		(15)
Total non-operating (benefit) expenses	$	(18,612)	$	(24,364)	$	399	$	486
Total expense (benefit) for retirement plans	$	(18,137)	$	(23,853)	$	414	$	517