Pension and other postretirement benefits (Tables)

6 Months Ended

Jun. 30, 2013

Net Benefit Cost of Pension and Postretirement Benefit Plans

Net benefit cost of pension and postretirement benefit plans consisted of the following:

	Pension Three Months  Ended						Postretirement Benefits Three  Months Ended				Pension Six Months Ended						Postretirement Benefits Six  Months Ended
	June  30, 2013			July 1, 2012			June  30, 2013		July 1, 2012		June  30, 2013			July 1, 2012			June  30, 2013		July 1, 2012
	(Dollars in thousands)
Service cost	$	464		$	711		$	161	$	158	$	929		$	1,389		$	325	$	316
Interest cost		4,142			4,125			542		473		8,281			8,251			1,541		946
Expected return on Plan assets		(5,774	)		(5,042	)		—		—		(11,544	)		(10,085	)		—		—
Net amortization and deferral		1,414			1,604			202		122		2,824			3,210			932		245
Settlement charge		—			(124	)		—		—		—			(124	)		—		—
Curtailment charge		—			111			—		—		—			111			—		—
Net benefit cost	$	246		$	1,385		$	905	$	753	$	490		$	2,752		$	2,798	$	1,507