SEGMENT AND GEOGRAPHIC DISCLOSURES - Segment Data for our Three Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Total Revenues	$ 239,492	$ 221,540	$ 441,769	$ 410,578
Total Operating income (loss)	4,596	(10,794)	(3,150)	(33,201)
Total Capital expenditures	2,269	4,966	4,297	10,588
Total Depreciation and amortization	9,539	9,009	19,085	18,463
IHT
Segment Reporting Information [Line Items]
Total Revenues	116,740	114,124	218,569	209,721
MS
Segment Reporting Information [Line Items]
Total Revenues	122,752	107,416	223,200	200,857
Operating segments | IHT
Segment Reporting Information [Line Items]
Total Revenues	116,740	114,124	218,569	209,721
Total Operating income (loss)	6,548	5,514	11,271	5,648
Total Capital expenditures	1,595	3,326	3,022	8,097
Total Depreciation and amortization	3,188	3,096	6,242	6,350
Operating segments | MS
Segment Reporting Information [Line Items]
Total Revenues	122,752	107,416	223,200	200,857
Total Operating income (loss)	12,720	6,984	15,913	7,497
Total Capital expenditures	674	1,621	1,275	2,434
Total Depreciation and amortization	4,704	4,634	9,457	9,518
Corporate and shared support services
Segment Reporting Information [Line Items]
Total Operating income (loss)	(14,672)	(23,292)	(30,334)	(46,346)
Total Capital expenditures	0	19	0	57
Total Depreciation and amortization	$ 1,647	$ 1,279	$ 3,386	$ 2,595