RESTRUCTURING CHARGES - Restructuring charges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 1,734	$ 4,895	$ 1,919	$ 9,104
Workforce reduction
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	1,685	4,895	1,868	9,055
Other restructuring costs
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 49	$ 0	$ 51	$ 49