Pension Plans - Pension plan net periodic benefit costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2022	Jul. 02, 2021	Jul. 01, 2022	Jul. 02, 2021
Defined Benefit Plan Disclosure
Increase (Decrease) in PBGC Premium				$ 3,900
Defined Benefit Plan, Service Cost Benefit				1,000
Qualified Pension Plan
Defined Benefit Plan Disclosure
Service cost(1)	$ (882)		$ (1,682)	(651)
Interest cost on projected benefit obligation	4,349	$ 3,558	8,599	7,083
Expected return on plan assets	(10,564)	(11,314)	(21,089)	(22,589)
Amortization of net loss	1,154	1,147	2,129	2,222
Net pension (income) cost	(4,179)	(7,258)	(8,679)	(12,633)
Defined Benefit Plan, Service Cost Benefit		649
SERP
Defined Benefit Plan Disclosure
Service cost(1)	0	0	0	0
Interest cost on projected benefit obligation	22	14	44	29
Expected return on plan assets	0	0	0	0
Amortization of net loss	15	18	30	35
Net pension (income) cost	$ 37	$ 32	$ 74	$ 64