Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 2013

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [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 September 30,	2013			2012			2013			2012
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	39		$	349		$	419		$	437
Interest cost	4,062			4,407			804			943
Expected return on assets	(4,979		)	(5,865		)	(1,086		)	(1,222		)
Amortization of prior service cost (credit)	18			(22		)	(364		)	(534		)
Amortization of net actuarial loss	1,793			1,887			327			356
Amortization of net transition obligation	—			—			—			531
Curtailment gain	—			(1,023		)	—			—
Net periodic benefit cost, including amount capitalized	933			(267		)	100			511
Less amount capitalized	157			185			47			314
Net periodic benefit cost (credit)	$	776		$	(452	)	$	53		$	197

							Other
							Postretirement
	Pension Benefits						Benefits
Nine Months Ended September 30,	2013			2012			2013			2012
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	116		$	1,044		$	1,257		$	1,310
Interest cost	12,186			13,223			2,411			3,124
Expected return on assets	(14,937		)	(17,596		)	(3,258		)	(3,667		)
Amortization of prior service cost (credit)	54			(64		)	(1,092		)	(1,078		)
Amortization of net actuarial loss	5,373			5,670			1,405			1,769
Amortization of net transition obligation	—			—			—			1,594
Curtailment gain	—			(1,023		)	—			—
Net periodic benefit cost, including amount capitalized	2,792			1,254			723			3,052
Less amount capitalized	425			615			137			635
Net periodic benefit cost	$	2,367		$	639		$	586		$	2,417