Pension plans and other postretirement benefits (Tables)

3 Months Ended

Mar. 31, 2019

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
	2019			2018			2019			2018
	(In thousands)
Service cost	$	4,087			5,103			200		226
Interest cost on projected benefit obligation		20,200			18,805			603			557
Expected return on plan assets		(30,600	)		(30,875	)		—			—
Amortization of prior service cost (credit)		125			125			(1,175	)		(1,175	)
Amortization of net actuarial loss (gain)		4,450			11,100			(300	)		(200	)
Net periodic cost (benefit)	$	(1,738	)		4,258			(672	)		(592	)