SEGMENT AND GEOGRAPHIC DISCLOSURES - Segment Data for our Three Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 251,265	$ 238,873	$ 469,841	$ 433,491
Operating income (loss)	(2,780)	(5,994)	(18,983)	(30,294)
Capital expenditures	6,299	5,094	12,930	9,491
Depreciation and amortization	9,578	10,347	19,609	21,306
IHT
Segment Reporting Information [Line Items]
Revenues	114,124	117,462	209,721	208,601
MS
Segment Reporting Information [Line Items]
Revenues	107,416	97,167	200,857	184,563
Quest Integrity
Segment Reporting Information [Line Items]
Revenues	29,725	24,244	59,263	40,327
Operating segments | IHT
Segment Reporting Information [Line Items]
Revenues		117,462		208,601
Operating income (loss)	5,514	7,395	5,648	7,759
Capital expenditures	3,326	2,457	8,097	5,171
Depreciation and amortization	3,096	3,270	6,350	6,740
Operating segments | MS
Segment Reporting Information [Line Items]
Revenues		97,167		184,563
Operating income (loss)	6,984	2,328	7,497	2,443
Capital expenditures	1,621	1,367	2,434	2,519
Depreciation and amortization	4,634	5,043	9,518	10,482
Operating segments | Quest Integrity
Segment Reporting Information [Line Items]
Revenues		24,244		40,327
Operating income (loss)	8,014	5,702	14,218	5,450
Capital expenditures	1,333	974	2,342	1,380
Depreciation and amortization	569	710	1,146	1,422
Corporate and shared support services
Segment Reporting Information [Line Items]
Operating income (loss)	(23,292)	(21,419)	(46,346)	(45,946)
Capital expenditures	19	296	57	421
Depreciation and amortization	$ 1,279	$ 1,324	$ 2,595	$ 2,662