Pension plans and other postretirement benefits (Tables)

6 Months Ended

Jun. 30, 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 June 30
	2019			2018			2019			2018
	(In thousands)
Service cost	$	4,559			5,069			229		243
Interest cost on projected benefit obligation		20,590			18,548			569			589
Expected return on plan assets		(30,470	)		(30,688	)		—			—
Amortization of prior service cost (credit)		154			153			(1,190	)		(1,189	)
Amortization of net actuarial loss (gain)		6,546			10,796			(323	)		(213	)
Net periodic cost (benefit)	$	1,379			3,878			(715	)		(570	)

	Pension Benefits						Other Postretirement Benefits
	Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands)
Service cost	$	8,646			10,172			429			469
Interest cost on projected benefit obligation		40,790			37,353			1,172			1,146
Expected return on plan assets		(61,070	)		(61,563	)		—			—
Amortization of prior service cost (credit)		279			278			(2,365	)		(2,364	)
Amortization of net actuarial loss (gain)		10,996			21,896			(623	)		(413	)
Net periodic cost (benefit)	$	(359	)		8,136			(1,387	)		(1,162	)