Employee benefit plans (Tables)

6 Months Ended

Jun. 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 June 30,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	227		$	340
Interest cost	3,840			3,488			713			672
Expected return on assets	(3,998		)	(5,379		)	(1,182		)	(1,266		)
Amortization of prior service credit	—			—			(228		)	(348		)
Amortization of net actuarial (gain) loss	1,418			1,721			(42		)	82
Net periodic benefit cost (credit), including amount capitalized	1,260			(170		)	(512		)	(520		)
Less amount capitalized	—			—			27			43
Net periodic benefit cost (credit)	$	1,260		$	(170	)	$	(539	)	$	(563	)

	Pension Benefits						Other Postretirement Benefits
Six Months Ended June 30,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	571		$	747
Interest cost	7,613			7,295			1,493			1,450
Expected return on assets	(9,118		)	(10,377		)	(2,402		)	(2,433		)
Amortization of prior service credit	—			—			(577		)	(697		)
Amortization of net actuarial loss	2,773			3,503			55			320
Net periodic benefit cost (credit), including amount capitalized	1,268			421			(860		)	(613		)
Less amount capitalized	—			—			58			83
Net periodic benefit cost (credit)	$	1,268		$	421		$	(918	)	$	(696	)