Employee benefit plans (Tables)

3 Months Ended

Mar. 31, 2019

Retirement Benefits [Abstract]

Schedule of net benefit costs

Components of net periodic benefit cost (credit) for the Company's pension and other postretirement benefit plans were as follows:

	Pension Benefits						Other Postretirement Benefits
Three Months Ended March 31,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	344		$	407
Interest cost	3,773			3,807			780			778
Expected return on assets	(5,120		)	(4,998		)	(1,220		)	(1,167		)
Amortization of prior service credit	—			—			(252		)	(349		)
Amortization of net actuarial loss	1,355			1,782			—			238
Net periodic benefit cost (credit), including amount capitalized	8			591			(348		)	(93		)
Less amount capitalized	—			—			31			40
Net periodic benefit cost (credit)	$	8		$	591		$	(379	)	$	(133	)