ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			$ 1,070,134
Net other comprehensive income/(loss)	$ (10,466)	$ (14,769)	1,356	$ (23,826)
Equity, ending balance	1,182,607		1,182,607
Income tax expense related to items of other comprehensive income/(loss)	128	379	405	899
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(191,300)	(179,600)
Other comprehensive income/(loss) before reclassifications			200	(26,700)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			0	0
Net other comprehensive income/(loss)			200	(26,700)
Equity, ending balance	(191,100)	(206,300)	(191,100)	(206,300)
Pension and Post-Retirement Plan Benefit Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(40,100)	(49,000)
Other comprehensive income/(loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			1,200	3,100
Net other comprehensive income/(loss)			1,200	3,100
Equity, ending balance	(38,900)	(45,900)	(38,900)	(45,900)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			(231,400)	(228,600)
Other comprehensive income/(loss) before reclassifications			200	(26,700)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			1,200	3,100
Net other comprehensive income/(loss)			1,400	(23,600)
Equity, ending balance	$ (230,000)	$ (252,200)	$ (230,000)	$ (252,200)