SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Comprehensive Income (Details) $ in Thousands	9 Months Ended
	Sep. 28, 2019 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	$ (303,185)
Balance at the end of the period	(316,717)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(230,261)
Current-period comprehensive income (loss)	(19,814)
Balance at the end of the period	(250,075)
Gain/(Loss) on Hedging Activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	11,171
Current-period comprehensive income (loss)	6,282
Balance at the end of the period	17,453
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(84,095)
Current-period comprehensive income (loss)	0
Balance at the end of the period	(84,095)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(303,185)
Current-period comprehensive income (loss)	(13,532)
Balance at the end of the period	$ (316,717)