Retirement Benefits (Tables)

3 Months Ended

Mar. 27, 2020

Defined Benefit Plan [Abstract]

Components of Net Periodic Benefit Cost

The components of net periodic benefit cost for retirement benefit plans were as follows (in thousands):

	Three Months Ended
	March 27, 2020			March 29, 2019
Pension Benefits
Service cost	$	2,422		$	2,009
Interest cost	3,407			3,738
Expected return on assets	(4,750		)	(4,359		)
Amortization and other	2,721			1,979
Net periodic benefit cost	$	3,800		$	3,367
Postretirement Medical
Service cost	$	175		$	150
Interest cost	248			317
Amortization	177			108
Net periodic benefit cost	$	600		$	575