Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 23, 2020	Aug. 25, 2019	Aug. 23, 2020	Aug. 25, 2019
Net periodic benefit cost:
Net periodic benefit cost	$ 2,339	$ 4,868	$ 6,714	$ 14,647
Total pension plan contributions	3,200		17,700
Pension benefits
Net periodic benefit cost:
Net periodic benefit cost	1,830	3,975	5,186	11,968
Postretirement benefits
Net periodic benefit cost:
Net periodic benefit cost	$ 509	$ 893	$ 1,528	$ 2,679