SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Comprehensive Income (Loss) (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018 USD ($)
Components of accumulated other comprehensive income (loss)
Beginning balance	$ 1,151,795
Current-period comprehensive income (loss)	(34,581)
Divestiture of grinding media business	10,418
Ending balance	1,135,523
Foreign Currency Translation Adjustments
Components of accumulated other comprehensive income (loss)
Beginning balance	(171,399)
Current-period comprehensive income (loss)	(68,065)
Divestiture of grinding media business	9,203
Ending balance	(230,261)
Gain on Hedging Activities
Components of accumulated other comprehensive income (loss)
Beginning balance	6,357
Current-period comprehensive income (loss)	3,599
Divestiture of grinding media business	1,215
Ending balance	11,171
Defined Benefit Pension Plan
Components of accumulated other comprehensive income (loss)
Beginning balance	(113,980)
Current-period comprehensive income (loss)	29,885
Divestiture of grinding media business	0
Ending balance	(84,095)
Accumulated Other Comprehensive Income (Loss)
Components of accumulated other comprehensive income (loss)
Beginning balance	(279,022)
Ending balance	$ (303,185)