Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [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,	2015			2014			2015			2014
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	32		$	454		$	379
Interest cost	4,285			4,420			902			919
Expected return on assets	(5,563		)	(5,304		)	(1,199		)	(1,154		)
Amortization of prior service cost (credit)	—			18			(343		)	(348		)
Amortization of net actuarial loss	1,734			1,217			511			162
Net periodic benefit cost (credit), including amount capitalized	456			383			325			(42		)
Less amount capitalized	90			27			36			(65		)
Net periodic benefit cost (credit)	$	366		$	356		$	289		$	23

	Pension Benefits						Other Postretirement Benefits
Nine Months Ended September 30,	2015			2014			2015			2014
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	86		$	96		$	1,362		$	1,138
Interest cost	12,855			13,265			2,705			2,701
Expected return on assets	(16,689		)	(15,913		)	(3,597		)	(3,463		)
Amortization of prior service cost (credit)	36			54			(1,028		)	(1,044		)
Amortization of net actuarial loss	5,282			3,651			1,525			486
Curtailment loss	258			—			—			—
Net periodic benefit cost (credit), including amount capitalized	1,828			1,153			967			(182		)
Less amount capitalized	219			195			98			(55		)
Net periodic benefit cost (credit)	$	1,609		$	958		$	869		$	(127	)