RESTRUCTURING ACTIVITIES - Restructuring Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 5,359	$ 7,359
Restructuring expense	11,849	11,707
Payments	(9,062)	(13,707)
Balance at end of period	$ 8,146	$ 5,359