Employee Benefit Plans (Tables)

6 Months Ended

Jun. 25, 2017

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 25, 2017			June 26, 2016			June 25, 2017			June 26, 2016
Pension and SERPA Benefits
Service cost	$	7,896		$	8,359		$	15,792		$	16,718
Interest cost	21,269			22,707			42,538			45,414
Expected return on plan assets	(35,345		)	(36,445		)	(70,690		)	(72,890		)
Amortization of unrecognized:
Prior service cost	254			255			508			510
Net loss	10,998			11,588			21,996			23,176
Settlement loss	—			300			—			600
Net periodic benefit cost	$	5,072		$	6,764		$	10,144		$	13,528
Postretirement Healthcare Benefits
Service cost	$	1,875		$	1,870		$	3,750		$	3,740
Interest cost	3,412			3,704			6,824			7,408
Expected return on plan assets	(3,156		)	(3,017		)	(6,312		)	(6,034		)
Amortization of unrecognized:
Prior service credit	(543		)	(701		)	(1,086		)	(1,402		)
Net loss	815			884			1,630			1,768
Net periodic benefit cost	$	2,403		$	2,740		$	4,806		$	5,480