ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	$ 1,253,971	$ 1,205,805	$ 1,269,813	$ 1,209,467	$ 1,171,965	$ 1,169,756	$ 1,269,813	$ 1,169,756
Other comprehensive (loss) income before reclassifications and tax impacts							(36,408)
Amounts reclassified out of accumulated other comprehensive loss							5,696
Tax gain (loss)							1,319
Other comprehensive income (loss), net of tax	12,385	17,528	(59,306)	(9,419)	5,076	4,024	(29,393)	(319)
Balance ending of period	1,304,715	1,253,971	1,205,805	1,235,795	1,209,467	1,171,965	1,304,715	1,235,795
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(187,795)				(187,795)
Other comprehensive (loss) income before reclassifications and tax impacts							(15,044)
Amounts reclassified out of accumulated other comprehensive loss							0
Tax gain (loss)							1,349
Other comprehensive income (loss), net of tax							(13,695)
Balance ending of period	(201,490)						(201,490)
Unrealized Gains (Losses) on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			143				143
Other comprehensive (loss) income before reclassifications and tax impacts							141
Amounts reclassified out of accumulated other comprehensive loss							0
Tax gain (loss)							(30)
Other comprehensive income (loss), net of tax							111
Balance ending of period	254						254
Unrealized Loss on Interest Rate Hedge
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(20,839)				(20,839)
Other comprehensive (loss) income before reclassifications and tax impacts							(21,505)
Amounts reclassified out of accumulated other comprehensive loss							5,696
Tax gain (loss)							0
Other comprehensive income (loss), net of tax							(15,809)
Balance ending of period	(36,648)						(36,648)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(1,560)				(1,560)
Other comprehensive (loss) income before reclassifications and tax impacts							0
Amounts reclassified out of accumulated other comprehensive loss							0
Tax gain (loss)							0
Other comprehensive income (loss), net of tax							0
Balance ending of period	(1,560)						(1,560)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	(251,829)	(269,357)	(210,051)	(214,271)	(219,347)	(223,371)	(210,051)	(223,371)
Other comprehensive income (loss), net of tax	12,385	17,528	(59,306)	(9,419)	5,076	4,024
Balance ending of period	$ (239,444)	$ (251,829)	$ (269,357)	$ (223,690)	$ (214,271)	$ (219,347)	$ (239,444)	$ (223,690)