EMPLOYEE BENEFITS - Contributions (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Aug. 31, 2019	May 31, 2018	Dec. 29, 2019	Dec. 29, 2019	Dec. 30, 2018	Dec. 27, 2020	Jan. 14, 2020
Subsequent event
Medical cost trend rates
Installment of contribution plan payable							$ 4,000,000
Pension plan
Weighted average assumptions used for valuing benefit obligations
Discount rate (as a percent)			3.48%	3.48%	4.42%
Weighted average assumptions used in calculating expense
Expected long-term return on plan assets (as a percent)				7.75%	7.75%
Discount rate (as a percent)				4.42%	3.91%
Medical cost trend rates
Voluntary cash contribution				$ 0	$ 0
Gain or loss recognized on the contribution of property				0
Proceeds from sale of real property location	$ 800,000	$ 4,100,000
Loss on sale of real property location				600,000	$ 200,000
Minimum cash contribution			$ 3,100,000
Expected benefit payments
2020			105,047,000	105,047,000
2021			126,706,000	126,706,000
2022			118,914,000	118,914,000
2023			119,193,000	119,193,000
2024			120,023,000	120,023,000
2025-2029			612,922,000	612,922,000
Total			$ 1,202,805,000	$ 1,202,805,000
Post-retirement plans
Weighted average assumptions used for valuing benefit obligations
Discount rate (as a percent)			3.15%	3.15%	4.15%
Weighted average assumptions used in calculating expense
Discount rate (as a percent)				4.15%	3.60%
Expected benefit payments
2020			$ 806,000	$ 806,000
2021			712,000	712,000
2022			629,000	629,000
2023			556,000	556,000
2024			488,000	488,000
2025-2029			1,663,000	1,663,000
Total			$ 4,854,000	$ 4,854,000
Forecast
Medical cost trend rates
Estimated minimum required contributions						$ 124,200,000