ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance	$ 948,662
Other comprehensive income/(loss)	9,524	$ (10,630)
Equity, ending balance	964,059
Income tax expense related to items of other comprehensive income/(loss)	260	232
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance	(179,600)	(152,200)
Other comprehensive income/(loss) before reclassifications	8,700	(11,400)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)	0	0
Other comprehensive income/(loss)	8,700	(11,400)
Equity, ending balance	(170,900)	(163,600)
Pension and Post-Retirement Plan Benefit Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance	(49,000)	(52,600)
Other comprehensive income/(loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income/(loss) (1)	900	900
Other comprehensive income/(loss)	900	900
Equity, ending balance	(48,100)	(51,700)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance	(228,600)	(204,800)
Other comprehensive income/(loss) before reclassifications	8,700	(11,400)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)	900	900
Other comprehensive income/(loss)	9,600	(10,500)
Equity, ending balance	$ (219,000)	$ (215,300)