Retirement Benefits (Tables)

9 Months Ended

Sep. 27, 2019

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						Nine Months Ended
	September 27, 2019			September 28, 2018			September 27, 2019			September 28, 2018
Pension Benefits
Service cost	$	2,161		$	2,165		$	5,805		$	6,376
Interest cost	3,711			3,227			11,021			10,072
Expected return on assets	(4,289		)	(4,369		)	(12,864		)	(13,087		)
Amortization and other	3,095			2,077			6,912			6,252
Net periodic benefit cost	$	4,678		$	3,100		$	10,874		$	9,613
Postretirement Medical
Service cost	$	136		$	127		$	409		$	477
Interest cost	291			284			872			813
Amortization	68			213			205			485
Net periodic benefit cost	$	495		$	624		$	1,486		$	1,775