Employee Benefit Plans (Tables)

9 Months Ended

Sep. 25, 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						Nine months ended
	September 25, 2016			September 27, 2015			September 25, 2016			September 27, 2015
Pension and SERPA Benefits
Service cost	$	8,359		$	10,010		$	25,077		$	30,030
Interest cost	22,707			21,836			68,121			65,508
Expected return on plan assets	(36,445		)	(36,232		)	(109,335		)	(108,696		)
Amortization of unrecognized:
Prior service cost	255			109			765			327
Net loss	11,588			13,678			34,764			41,031
Settlement loss	300			—			900			—
Net periodic benefit cost	$	6,764		$	9,401		$	20,292		$	28,200
Postretirement Healthcare Benefits
Service cost	$	1,870		$	2,065		$	5,610		$	6,195
Interest cost	3,704			3,541			11,112			10,623
Expected return on plan assets	(3,017		)	(2,877		)	(9,051		)	(8,631		)
Amortization of unrecognized:
Prior service credit	(701		)	(804		)	(2,103		)	(2,412		)
Net loss	884			993			2,652			2,979
Net periodic benefit cost	$	2,740		$	2,918		$	8,220		$	8,754