ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period	$ 1,348,450	$ 1,341,551	$ 1,205,805	$ 1,269,813	$ 1,341,551	$ 1,269,813
Other comprehensive income (loss) before reclassifications					17,613
Amounts reclassified out of accumulated other comprehensive loss					4,942
Tax benefit					33
Other comprehensive income (loss), net of tax	10,640	11,948	17,528	(59,306)	22,588	(41,778)
Balance ending of period	1,409,587	1,348,450	1,253,971	1,205,805	1,409,587	1,253,971
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period		(176,234)			(176,234)
Other comprehensive income (loss) before reclassifications					15,009
Amounts reclassified out of accumulated other comprehensive loss					0
Tax benefit					0
Other comprehensive income (loss), net of tax					15,009
Balance ending of period	(161,225)				(161,225)
Unrealized Gains (Losses) on Available-For-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period		135			135
Other comprehensive income (loss) before reclassifications					(155)
Amounts reclassified out of accumulated other comprehensive loss					0
Tax benefit					33
Other comprehensive income (loss), net of tax					(122)
Balance ending of period	13				13
Unrealized (Losses) Gains on Interest Rate Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period		(33,629)			(33,629)
Other comprehensive income (loss) before reclassifications					2,759
Amounts reclassified out of accumulated other comprehensive loss					4,942
Tax benefit					0
Other comprehensive income (loss), net of tax					7,701
Balance ending of period	(25,928)				(25,928)
Unrealized Losses on Unfunded Pension Liability
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period		(1,749)			(1,749)
Other comprehensive income (loss) before reclassifications					0
Amounts reclassified out of accumulated other comprehensive loss					0
Tax benefit					0
Other comprehensive income (loss), net of tax					0
Balance ending of period	(1,749)				(1,749)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning of period	(199,529)	(211,477)	(269,357)	(210,051)	(211,477)	(210,051)
Other comprehensive income (loss), net of tax	10,640	11,948	17,528	(59,306)
Balance ending of period	$ (188,889)	$ (199,529)	$ (251,829)	$ (269,357)	$ (188,889)	$ (251,829)