Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 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 September 30,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	286		$	374
Interest cost	3,806			3,648			746			725
Expected return on assets	(4,559		)	(5,188		)	(1,201		)	(1,217		)
Amortization of prior service credit	—			—			(289		)	(349		)
Amortization of net actuarial loss	1,387			1,751			27			160
Net periodic benefit cost (credit), including amount capitalized	634			211			(431		)	(307		)
Less amount capitalized	—			—			26			46
Net periodic benefit cost (credit)	$	634		$	211		$	(457	)	$	(353	)

	Pension Benefits						Other Postretirement Benefits
Nine Months Ended September 30,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	857		$	1,121
Interest cost	11,419			10,943			2,239			2,175
Expected return on assets	(13,677		)	(15,565		)	(3,603		)	(3,650		)
Amortization of prior service credit	—			—			(866		)	(1,046		)
Amortization of net actuarial loss	4,160			5,254			82			480
Net periodic benefit cost (credit), including amount capitalized	1,902			632			(1,291		)	(920		)
Less amount capitalized	—			—			84			128
Net periodic benefit cost (credit)	$	1,902		$	632		$	(1,375	)	$	(1,048	)