Pension plans and other postretirement benefits (Tables)

9 Months Ended

Sep. 30, 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 September 30
	2021			2020			2021			2020
	(In thousands)
Service cost	$	5,128			4,986			254			242
Interest cost on projected benefit obligation		15,468			17,855			328			436
Expected return on plan assets		(35,862	)		(31,378	)		—			—
Amortization of prior service cost (credit)		139			125			(1,185	)		(1,175	)
Amortization of net actuarial loss (gain)		22,254			13,950			(324	)		(300	)
Net periodic cost (benefit)	$	7,127			5,538			(927	)		(797	)

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended September 30
	2021			2020			2021			2020
	(In thousands)
Service cost	$	15,385			14,958			760			727
Interest cost on projected benefit obligation		46,404			53,565			984			1,306
Expected return on plan assets		(107,586	)		(94,134	)		—			—
Amortization of prior service cost (credit)		415			404			(3,554	)		(3,544	)
Amortization of net actuarial loss (gain)		66,763			42,998			(971	)		(918	)
Net periodic cost (benefit)	$	21,381			17,791			(2,781	)		(2,429	)