Pension plans and other postretirement benefits (Tables)

6 Months Ended

Jun. 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 June 30
	2021			2020			2021			2020
	(In thousands)
Service cost	$	5,234			5,258			258			262
Interest cost on projected benefit obligation		15,502			17,824			329			451
Expected return on plan assets		(35,774	)		(31,281	)		—			—
Amortization of prior service cost (credit)		151			154			(1,194	)		(1,194	)
Amortization of net actuarial loss (gain)		22,359			15,098			(347	)		(318	)
Net periodic cost (benefit)	$	7,472			7,053			(954	)		(799	)

	Pension Benefits						Other Postretirement Benefits
	Six Months Ended June 30
	2021			2020			2021			2020
	(In thousands)
Service cost	$	10,257			9,972			506			485
Interest cost on projected benefit obligation		30,936			35,710			656			870
Expected return on plan assets		(71,724	)		(62,756	)		—			—
Amortization of prior service cost (credit)		276			279			(2,369	)		(2,369	)
Amortization of net actuarial loss (gain)		44,509			29,048			(647	)		(618	)
Net periodic cost (benefit)	$	14,254			12,253			(1,854	)		(1,632	)