RESTRUCTURING AND OTHER RELATED CHARGES - Schedule of Restructuring Charges by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	$ 3,365	$ 1,676	$ 6,727
OneTEAM Program
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	3,365	1,676	6,727
OneTEAM Program | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	3,365	1,700
OneTEAM Program | Employee Severance | IHT
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	922	249	2,995
OneTEAM Program | Employee Severance | MS
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	1,926	418	2,514
OneTEAM Program | Employee Severance | Quest Integrity
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	0	62	418
OneTEAM Program | Employee Severance | Corporate and shared support services
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges (credits), net	$ 517	$ 947	$ 800