EQUITY - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period	$ (80,868)
Other comprehensive loss before reclassifications	(11,944)
Cumulative adjustment upon adoption of ASU 2017-12		$ (576)
Amounts reclassified from accumulated other comprehensive loss	1,944
Net current period other comprehensive income (loss)	(10,000)	$ (6,446)
Balance at the end of the period	(90,868)
Pension and Post-Retirement Obligations
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period	(64,316)
Amounts reclassified from accumulated other comprehensive loss	336
Net current period other comprehensive income (loss)	336
Balance at the end of the period	(63,980)
Derivative Instruments
Accumulated other comprehensive loss, net of tax, by component
Balance at the beginning of the period	(16,552)
Other comprehensive loss before reclassifications	(11,944)
Amounts reclassified from accumulated other comprehensive loss	1,608
Net current period other comprehensive income (loss)	(10,336)
Balance at the end of the period	$ (26,888)