SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Pension Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Net periodic (benefit) expense:
Interest cost	$ 3,124	$ 4,345
Expected return on plan assets	(5,598)	(5,135)
Amortization of actuarial loss	711	658
Net periodic (benefit) expense	$ (1,763)	$ (132)