Pension plans and other postretirement benefits (Tables)

3 Months Ended

Mar. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Net Periodic Defined Benefit Cost for Defined Benefit Plans

Net periodic defined benefit cost for defined benefit plans consisted of the following:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended March 31
	2021			2020			2021			2020
	(In thousands)
Service cost	$	5,023			4,714			248		223
Interest cost on projected benefit obligation		15,434			17,886			327			419
Expected return on plan assets		(35,950	)		(31,475	)		—			—
Amortization of prior service cost (credit)		125			125			(1,175	)		(1,175	)
Amortization of net actuarial loss (gain)		22,150			13,950			(300	)		(300	)
Net periodic cost (benefit)	$	6,782			5,200			(900	)		(833	)