Employee Benefit Plans (Tables)

9 Months Ended

Sep. 24, 2017

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Costs

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

	Three months ended						Nine months ended
	September 24, 2017			September 25, 2016			September 24, 2017			September 25, 2016
Pension and SERPA Benefits
Service cost	$	7,896		$	8,359		$	23,688		$	25,077
Interest cost	21,269			22,707			63,807			68,121
Expected return on plan assets	(35,345		)	(36,445		)	(106,035		)	(109,335		)
Amortization of unrecognized:
Prior service cost	256			255			764			765
Net loss	10,998			11,588			32,994			34,764
Settlement loss	—			300			—			900
Net periodic benefit cost	$	5,074		$	6,764		$	15,218		$	20,292
Postretirement Healthcare Benefits
Service cost	$	1,875		$	1,870		$	5,625		$	5,610
Interest cost	3,412			3,704			10,236			11,112
Expected return on plan assets	(3,156		)	(3,017		)	(9,468		)	(9,051		)
Amortization of unrecognized:
Prior service credit	(543		)	(701		)	(1,629		)	(2,103		)
Net loss	815			884			2,445			2,652
Net periodic benefit cost	$	2,403		$	2,740		$	7,209		$	8,220