ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	$ 702,621
Other comprehensive income/(loss), net of tax	(33,944)	$ 20,141	$ (8,469)
Balance	735,827	702,621
Tax (benefit)/expense	300	500	500
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(99,700)	(118,400)	(110,100)
Other comprehensive income/(loss) before reclassifications	(34,800)	18,700	(8,300)
Amounts reclassified from accumulated other comprehensive income/(loss)	0	0	0
Other comprehensive income/(loss), net of tax	(34,800)	18,700	(8,300)
Balance	(134,500)	(99,700)	(118,400)
Pension and Post-Retirement Plan Benefit Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(49,300)	(51,500)	(51,500)
Other comprehensive income/(loss) before reclassifications	0	0	0
Amounts reclassified from accumulated other comprehensive income/(loss)	800	2,200	0
Other comprehensive income/(loss), net of tax	800	2,200	0
Balance	(48,500)	(49,300)	(51,500)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(149,000)	(169,900)	(161,600)
Other comprehensive income/(loss) before reclassifications	(34,800)	18,700	(8,300)
Amounts reclassified from accumulated other comprehensive income/(loss)	800	2,200	0
Other comprehensive income/(loss), net of tax	(34,000)	20,900	(8,300)
Balance	$ (183,000)	$ (149,000)	$ (169,900)