Pension and Postretirement Benefit Obligations - Components of Net Periodic Pension Cost (Detail) - Pension Plans - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,659	$ 1,207	$ 4,976	$ 3,620
Interest cost	2,760	3,063	8,280	9,188
Expected return on plan assets	(3,382)	(2,574)	(10,148)	(7,722)
Recognized net actuarial loss	1,189	901	3,568	2,702
Amortization of prior service cost	5	5	14	17
Net periodic pension/postretirement benefit cost	$ 2,231	$ 2,602	$ 6,690	$ 7,805