Employee Benefit Plans (Tables)

6 Months Ended

Jun. 26, 2016

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Costs

Components of net periodic benefit costs were as follows (in thousands):

	Three months ended						Six months ended
	June 26, 2016			June 28, 2015			June 26, 2016			June 28, 2015
Pension and SERPA Benefits
Service cost	$	8,359		$	10,010		$	16,718		$	20,020
Interest cost	22,707			21,836			45,414			43,672
Expected return on plan assets	(36,445		)	(36,232		)	(72,890		)	(72,465		)
Amortization of unrecognized:
Prior service cost	255			109			510			218
Net loss	11,588			13,677			23,176			27,354
Settlement loss	300			—			600			—
Net periodic benefit cost	$	6,764		$	9,400		$	13,528		$	18,799
Postretirement Healthcare Benefits
Service cost	$	1,870		$	2,065		$	3,740		$	4,130
Interest cost	3,704			3,541			7,408			7,082
Expected return on plan assets	(3,017		)	(2,877		)	(6,034		)	(5,754		)
Amortization of unrecognized:
Prior service credit	(701		)	(804		)	(1,402		)	(1,608		)
Net loss	884			993			1,768			1,986
Net periodic benefit cost	$	2,740		$	2,918		$	5,480		$	5,836