ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	$ 735,827
Other comprehensive income/(loss), net of tax	(7,163)	$ (33,944)	$ 20,141
Balance	798,669	735,827
Tax (benefit)/expense	(600)	300	500
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(134,500)	(99,700)	(118,400)
Other comprehensive income/(loss) before reclassifications	(5,700)	(34,800)	18,700
Amounts reclassified from accumulated other comprehensive income/(loss)	0	0	0
Other comprehensive income/(loss), net of tax	(5,700)	(34,800)	18,700
Balance	(140,200)	(134,500)	(99,700)
Pension and Post-Retirement Plan Benefit Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(48,500)	(49,300)	(51,500)
Other comprehensive income/(loss) before reclassifications	0	0	0
Amounts reclassified from accumulated other comprehensive income/(loss)	(1,500)	800	2,200
Other comprehensive income/(loss), net of tax	(1,500)	800	2,200
Balance	(50,000)	(48,500)	(49,300)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Balance	(183,000)	(149,000)	(169,900)
Other comprehensive income/(loss) before reclassifications	(5,700)	(34,800)	18,700
Amounts reclassified from accumulated other comprehensive income/(loss)	(1,500)	800	2,200
Other comprehensive income/(loss), net of tax	(7,200)	(34,000)	20,900
Balance	$ (190,200)	$ (183,000)	$ (149,000)