ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	$ 1,209,467	$ 1,171,965	$ 1,169,756	$ 1,161,048	$ 1,145,526	$ 1,188,202	$ 1,169,756	$ 1,188,202
Other comprehensive income (loss) before tax effects							(1,960)
Tax impact related to items in other comprehensive income (loss)							(60)
Amounts reclassified out of accumulated other comprehensive loss							1,701
Other comprehensive (loss) income	(9,419)	5,076	4,024	8,590	(4,942)	(16,746)	(319)	(13,098)
Balance ending of period	1,235,795	1,209,467	1,171,965	1,197,324	1,161,048	1,145,526	1,235,795	1,197,324
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(212,925)				(212,925)
Other comprehensive income (loss) before tax effects							15,960
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							0
Other comprehensive (loss) income							15,960
Balance ending of period	(196,965)						(196,965)
Unrealized (Losses) Gains on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(69)				(69)
Other comprehensive income (loss) before tax effects							(24)
Tax impact related to items in other comprehensive income (loss)							(60)
Amounts reclassified out of accumulated other comprehensive loss							332
Other comprehensive (loss) income							248
Balance ending of period	179						179
Unrealized Losses on Interest Rate Hedge
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(8,773)				(8,773)
Other comprehensive income (loss) before tax effects							(17,896)
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							1,369
Other comprehensive (loss) income							(16,527)
Balance ending of period	(25,300)						(25,300)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(1,604)				(1,604)
Other comprehensive income (loss) before tax effects							0
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							0
Other comprehensive (loss) income							0
Balance ending of period	(1,604)						(1,604)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	(214,271)	(219,347)	(223,371)	(194,095)	(189,153)	(172,407)	(223,371)	(172,407)
Other comprehensive (loss) income	(9,419)	5,076	4,024	8,590	(4,942)	(16,746)
Balance ending of period	$ (223,690)	$ (214,271)	$ (219,347)	$ (185,505)	$ (194,095)	$ (189,153)	$ (223,690)	$ (185,505)