ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Equity, beginning balance			$ 948,662
Other comprehensive income/(loss)	$ (18,581)	$ 9,020	(9,057)	$ (1,610)
Equity, ending balance	988,573		988,573
Income tax expense related to items of other comprehensive income/(loss)	260	232	520	464
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			(10,700)	(3,300)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			0	0
Other comprehensive income/(loss)			(10,700)	(3,300)
Equity, ending balance	(190,300)	(155,500)	(190,300)	(155,500)
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)			1,800	1,800
Other comprehensive income/(loss)			1,800	1,800
Equity, ending balance	(47,200)	(50,800)	(47,200)	(50,800)
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			(10,700)	(3,300)
Amounts reclassified from accumulated other comprehensive income/(loss) (1)			1,800	1,800
Other comprehensive income/(loss)			(8,900)	(1,500)
Equity, ending balance	$ (237,500)	$ (206,300)	$ (237,500)	$ (206,300)