ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Equity
Beginning balance	$ 1,341,551	$ 1,269,813	$ 1,169,756
Other comprehensive (loss) income before reclassifications	5,695	(11,023)	10,719
Amounts reclassified out of accumulated other comprehensive loss	10,011	8,180	2,667
Tax benefit (expense)	(241)	1,417	(66)
Other comprehensive income (loss), net of tax	15,465	(1,426)	13,320
Ending balance	1,513,887	1,341,551	1,269,813
Foreign Currency Translation Adjustments
Increase (Decrease) in Equity
Beginning balance	(176,234)	(187,795)	(212,925)
Other comprehensive (loss) income before reclassifications	(1,590)	10,212	25,130
Amounts reclassified out of accumulated other comprehensive loss	0	0	0
Tax benefit (expense)	0	1,349	0
Other comprehensive income (loss), net of tax	(1,590)	11,561	25,130
Ending balance	(177,824)	(176,234)	(187,795)
Unrealized (loss) gain on Available-for-Sale Securities
Increase (Decrease) in Equity
Beginning balance	135	143	(69)
Other comprehensive (loss) income before reclassifications	(361)	(10)	(70)
Amounts reclassified out of accumulated other comprehensive loss	0	0	332
Tax benefit (expense)	76	2	(50)
Other comprehensive income (loss), net of tax	(285)	(8)	212
Ending balance	(150)	135	143
Unrealized loss on Interest Rate Hedge
Increase (Decrease) in Equity
Beginning balance	(33,629)	(20,839)	(8,773)
Other comprehensive (loss) income before reclassifications	6,235	(20,970)	(14,401)
Amounts reclassified out of accumulated other comprehensive loss	10,011	8,180	2,335
Tax benefit (expense)	0	0	0
Other comprehensive income (loss), net of tax	16,246	(12,790)	(12,066)
Ending balance	(17,383)	(33,629)	(20,839)
Unrealized (loss) gain on unfunded pension liability
Increase (Decrease) in Equity
Beginning balance	(1,749)	(1,560)	(1,604)
Other comprehensive (loss) income before reclassifications	1,411	(255)	60
Amounts reclassified out of accumulated other comprehensive loss	0	0	0
Tax benefit (expense)	(317)	66	(16)
Other comprehensive income (loss), net of tax	1,094	(189)	44
Ending balance	(655)	(1,749)	(1,560)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Equity
Beginning balance	(211,477)	(210,051)	(223,371)
Other comprehensive income (loss), net of tax	15,465	(1,426)	13,320
Ending balance	$ (196,012)	$ (211,477)	$ (210,051)