EMPLOYEE BENEFITS (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 29, 2016 USD ($)	Sep. 25, 2016 USD ($)	Sep. 27, 2015 USD ($)	Sep. 25, 2016 USD ($) item	Sep. 27, 2015 USD ($)
EMPLOYEE BENEFITS
Number of new participants | item				0
Retirement expense for continuing operations
Net pension expense		$ 3,694	$ 2,492	$ 11,082	$ 7,478
Pension plan
Retirement expense for continuing operations
Service cost		4,700	2,920	14,100	8,760
Interest cost		22,167	21,248	66,501	63,745
Expected return on plan assets		(27,107)	(26,571)	(81,322)	(79,712)
Actuarial loss		4,596	5,548	13,787	16,645
Net pension expense		4,356	3,145	13,066	9,438
Value of contributions to plan	$ 47,100
Post-retirement plans
Retirement expense for continuing operations
Net pension expense		$ (662)	$ (653)	$ (1,984)	$ (1,960)