SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND PRACTICES - Additional Information (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Dec. 01, 2018 USD ($)	Jun. 30, 2019 USD ($) employee country Location	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) employee country segment Location customer	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment				3
Number of locations in which company operates (more than) | Location		200		200
Number of countries in which the company operates | country		20		20
Number of employees (approximately) | employee		6,500		6,500
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment loss	$ 0
Goodwill		$ 282,156		$ 282,156		$ 281,650
Accumulated impairment loss		75,200		75,200		75,200
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes		(997)	$ (4,106)	(664)	$ (9,064)
Pre-tax loss		(5,105)	$ 35,447	$ 18,790	$ 52,669
Sales Revenue, Net | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Number of customers accounted for more than specified percentage of consolidated revenues | customer				0
IHT
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill		193,199		$ 193,199		192,608
Accumulated impairment loss		21,100		21,100		21,100
MS
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill		55,540		55,540		55,627
Accumulated impairment loss		$ 54,100		$ 54,100		$ 54,100