EMPLOYEE BENEFITS - Retirement and Post retirement costs (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 29, 2016 USD ($)	Jun. 25, 2017 USD ($)	Jun. 26, 2016 USD ($)	Jun. 25, 2017 USD ($) item	Jun. 26, 2016 USD ($)
Retirement expense for continuing operations
Net pension expense		$ 3,328,000	$ 3,694,000	$ 6,655,000	$ 7,388,000
Pension plan
EMPLOYEE BENEFITS
Number of new participants | item				0
Further benefits		0		$ 0
Retirement expense for continuing operations
Interest cost		21,367,000	22,167,000	42,734,000	44,334,000
Expected return on plan assets		(22,393,000)	(22,408,000)	(44,785,000)	(44,815,000)
Actuarial loss		5,084,000	4,595,000	10,168,000	9,191,000
Net pension expense		4,058,000	4,354,000	8,117,000	8,710,000
Value of contributions to plan	$ 47,100,000
Post-retirement plans
Retirement expense for continuing operations
Net pension expense		(730,000)	$ (660,000)	(1,462,000)	$ (1,322,000)
Adjustments for New Accounting Principle, Early Adoption | Accounting Standards Update 2017 07 | Pension plan
Retirement expense for continuing operations
Service cost		(4,700,000)		(9,700,000)
Expected return on plan assets		$ 4,700,000		$ 9,400,000