ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			$ 735,827
Other comprehensive income/(loss)	$ (13,184)	$ (10,140)	(13,615)	$ (34,682)
Equity, ending balance	777,056		777,056
Income tax expense related to items of other comprehensive income/(loss)	131	176	413	529
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(134,500)	(99,700)
Other comprehensive income/(loss) before reclassifications			(15,100)	(36,600)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			0	0
Other comprehensive income/(loss)			(15,100)	(36,600)
Equity, ending balance	(149,600)	(136,300)	(149,600)	(136,300)
Pension and Post-Retirement Plan Benefit Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(48,500)	(49,300)
Other comprehensive income/(loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			1,500	1,800
Other comprehensive income/(loss)			1,500	1,800
Equity, ending balance	(47,000)	(47,500)	(47,000)	(47,500)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(183,000)	(149,000)
Other comprehensive income/(loss) before reclassifications			(15,100)	(36,600)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			1,500	1,800
Other comprehensive income/(loss)			(13,600)	(34,800)
Equity, ending balance	$ (196,600)	$ (183,800)	$ (196,600)	$ (183,800)