ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Loss by Component (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,169,756
Other comprehensive income (loss) before tax effects	8,071
Tax impact related to items in other comprehensive income (loss)	(58)
Amounts reclassified out of accumulated other comprehensive loss	1,087
Other comprehensive income	9,100
Balance at end of period	1,209,467
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(212,925)
Other comprehensive income (loss) before tax effects	22,137
Tax impact related to items in other comprehensive income (loss)	0
Amounts reclassified out of accumulated other comprehensive loss	0
Other comprehensive income	22,137
Balance at end of period	(190,788)
Unrealized (Losses) Gains on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(69)
Other comprehensive income (loss) before tax effects	(35)
Tax impact related to items in other comprehensive income (loss)	(58)
Amounts reclassified out of accumulated other comprehensive loss	332
Other comprehensive income	239
Balance at end of period	170
Unrealized Losses on Interest Rate Hedge
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(8,773)
Other comprehensive income (loss) before tax effects	(14,031)
Tax impact related to items in other comprehensive income (loss)	0
Amounts reclassified out of accumulated other comprehensive loss	755
Other comprehensive income	(13,276)
Balance at end of period	(22,049)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(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 income	0
Balance at end of period	(1,604)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(223,371)
Balance at end of period	$ (214,271)