EQUITY - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period			$ (109,418)				$ (109,418)
Other comprehensive loss before reclassifications							90
Amounts reclassified from accumulated other comprehensive loss							9,781
Net current period other comprehensive income	$ 2,376	$ 3,584	3,911	$ 2,523	$ 2,449	$ (10,000)	9,871
Balance at the end of the period	(99,547)						(99,547)
Pension and Post-Retirement Obligations
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period			(90,887)				(90,887)
Amounts reclassified from accumulated other comprehensive loss							848
Net current period other comprehensive income							848
Balance at the end of the period	(90,039)						(90,039)
Derivative Instruments
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period			$ (18,531)				(18,531)
Other comprehensive loss before reclassifications							90
Amounts reclassified from accumulated other comprehensive loss							8,933
Net current period other comprehensive income							9,023
Balance at the end of the period	$ (9,508)						$ (9,508)