Pension Benefits (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 29, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Components of Net Periodic Benefit Costs for the Pension Plans
Service cost		$ 1,129	$ 1,395	$ 3,387	$ 4,186
Interest cost		590	699	1,768	2,094
Expected return on plan assets that reduces periodic pension benefit cost		(434)	(393)	(1,301)	(1,180)
Amortization of prior service cost		4	4	13	13
Amortization of net actuarial loss		238	239	713	718
Settlements		1,282	0	1,282	0
Net periodic benefit cost		$ 2,809	$ 1,944	$ 5,862	$ 5,831
Pension plans, net gain (loss) amortization threshold		10.00%		10.00%
Subsequent Event [Member]
Components of Net Periodic Benefit Costs for the Pension Plans
Employer contributions	$ 5,900