ACCUMULATED OTHER COMPREHENSIVE LOSS (Components of AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Equity
Beginning balance	$ 1,188,202	$ 1,084,241	$ 1,096,282
Other comprehensive income (loss) before reclassifications	(56,647)	41,966	23,648
Amounts reclassified out of accumulated other comprehensive loss	806	222	0
Tax benefit (loss)	4,877	(269)	16,918
Other comprehensive income (loss)	(50,964)	41,919	40,566
Ending balance	1,169,756	1,188,202	1,084,241
Foreign Currency Translation Adjustments
Increase (Decrease) in Equity
Beginning balance	(170,575)	(212,211)	(252,939)
Other comprehensive income (loss) before reclassifications	(47,374)	41,636	23,967
Amounts reclassified out of accumulated other comprehensive loss	0	0	0
Tax benefit (loss)	5,024	0	16,761
Other comprehensive income (loss)	(42,350)	41,636	40,728
Ending balance	(212,925)	(170,575)	(212,211)
Unrealized (Losses) Gains on Available-for-Sale Securities
Increase (Decrease) in Equity
Beginning balance	(146)	(321)	0
Other comprehensive income (loss) before reclassifications	182	184	(535)
Amounts reclassified out of accumulated other comprehensive loss	0	222	0
Tax benefit (loss)	(105)	(231)	214
Other comprehensive income (loss)	77	175	(321)
Ending balance	(69)	(146)	(321)
Unrealized Loss on Interest Rate Hedge
Increase (Decrease) in Equity
Beginning balance	0	0	0
Other comprehensive income (loss) before reclassifications	(9,579)	0	0
Amounts reclassified out of accumulated other comprehensive loss	806	0	0
Tax benefit (loss)	0	0	0
Other comprehensive income (loss)	(8,773)	0	0
Ending balance	(8,773)	0	0
Unfunded Pension Liability
Increase (Decrease) in Equity
Beginning balance	(1,686)	(1,794)	(1,953)
Other comprehensive income (loss) before reclassifications	124	146	216
Amounts reclassified out of accumulated other comprehensive loss	0	0	0
Tax benefit (loss)	(42)	(38)	(57)
Other comprehensive income (loss)	82	108	159
Ending balance	(1,604)	(1,686)	(1,794)
Accumulated Other Comprehensive loss
Increase (Decrease) in Equity
Beginning balance	(172,407)	(214,326)	(254,892)
Other comprehensive income (loss)	(50,964)	41,919	40,566
Ending balance	$ (223,371)	$ (172,407)	$ (214,326)

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