RESTRUCTURING (Details) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1,600,000	$ 2,100,000	$ 5,800,000	$ 0	$ 1,646,000	$ 7,828,000
Reduction in workforce related to restructuring (percent)	7.00%
Restructuring Reserve [Roll Forward]
Accrued charges, beginning of period	$ 4,685,000			1,315,000	4,685,000	337,000
Costs incurred	1,600,000	2,100,000	$ 5,800,000	0	1,646,000	7,828,000
Costs paid				(526,000)	(5,016,000)	(3,480,000)
Accrued charges, end of period		4,685,000		789,000	1,315,000	4,685,000
Severance Charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges				0	1,646,000	5,457,000
Restructuring Reserve [Roll Forward]
Accrued charges, beginning of period	3,896,000			526,000	3,896,000	337,000
Costs incurred				0	1,646,000	5,457,000
Costs paid				(526,000)	(5,016,000)	(1,898,000)
Accrued charges, end of period		3,896,000		0	526,000	3,896,000
Other Associated Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				0	0	2,371,000
Restructuring Reserve [Roll Forward]
Accrued charges, beginning of period	$ 789,000			789,000	789,000	0
Costs incurred				0	0	2,371,000
Costs paid				0	0	(1,582,000)
Accrued charges, end of period		$ 789,000		$ 789,000	$ 789,000	$ 789,000