Employee benefit plans (Tables)

3 Months Ended

Mar. 31, 2015

Compensation and Retirement Disclosure [Abstract]

Schedule of net benefit costs

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

							Other
							Postretirement
	Pension Benefits						Benefits
Three Months Ended March 31,	2015			2014			2015			2014
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	40		$	33		$	483		$	379
Interest cost	4,364			4,440			914			858
Expected return on assets	(5,373		)	(5,125		)	(1,175		)	(1,067		)
Amortization of prior service cost (credit)	18			18			(342		)	(348		)
Amortization of net actuarial loss	1,735			1,313			461			318
Net periodic benefit cost, including amount capitalized	784			679			341			140
Less amount capitalized	76			95			29			29
Net periodic benefit cost	$	708		$	584		$	312		$	111