Pension Benefits (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Components of Net Periodic Benefit Costs for the Pension Plans
Service cost		$ 863	$ 1,108	$ 2,258	$ 2,791
Interest cost		480	739	1,178	1,395
Expected return on plan assets that reduces periodic pension benefit cost		(474)	(321)	(867)	(787)
Amortization of prior service cost		5	5	9	9
Amortization of net actuarial loss		235	147	475	479
Net periodic benefit cost		$ 1,109	$ 1,678	$ 3,053	$ 3,887
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	$ 4,600