Pension Benefits - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2022	Dec. 26, 2021	Dec. 27, 2020
Pension Benefits
Benefit obligation	$ 236,300
Pension settlement charges	$ 80,600
Pension Plan
Pension Benefits
Service cost		$ 11,631	$ 9,200	$ 10,548
Interest cost		40,492	34,869	50,311
Expected return on plan assets		(55,229)	(50,711)	(67,146)
Amortization and other costs		19,637	27,500	27,959
Amortization of prior service (credit)/cost		(1,897)	(1,890)	(1,894)
Effect of settlement/curtailment		0	(163)	80,079
Net periodic pension cost		14,634	18,805	99,857
Benefit obligation		1,256,020	1,714,954	1,808,605
Qualified Plans | Pension Plan
Pension Benefits
Service cost		11,526	9,105	10,429
Interest cost		35,350	30,517	43,710
Expected return on plan assets		(55,229)	(50,711)	(67,146)
Amortization and other costs		13,065	20,225	21,887
Amortization of prior service (credit)/cost		(1,945)	(1,945)	(1,945)
Effect of settlement/curtailment		0	0	80,641
Net periodic pension cost		2,767	7,191	87,576
Benefit obligation		1,076,412	1,475,764	1,549,012
Non- Qualified Plans | Pension Plan
Pension Benefits
Service cost		105	95	119
Interest cost		5,142	4,352	6,601
Expected return on plan assets		0	0	0
Amortization and other costs		6,572	7,275	6,072
Amortization of prior service (credit)/cost		48	55	51
Effect of settlement/curtailment		0	(163)	(562)
Net periodic pension cost		11,867	11,614	12,281
Benefit obligation		$ 179,608	$ 239,190	$ 259,593