BUSINESS COMBINATION (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Consideration paid and the fair value of assets acquired and liabilities assumed
Goodwill	$ 210,466	$ 207,177
Field and Industrial Services
Consideration paid and the fair value of assets acquired and liabilities assumed
Goodwill	51,231	51,231
Winnie
Consideration paid and the fair value of assets acquired and liabilities assumed
Current assets	1,860	1,923
Property and equipment	3,976	6,300
Identifiable intangible assets	66,500	66,600
Current liabilities	(755)	(755)
Other liabilities	(512)	(512)
Total identifiable net assets	71,069	73,556
Goodwill	16,159	13,573
Total purchase price	87,228	$ 87,129
Adjustments
Current assets - adjustment	(63)
Property and equipment - adjustment	(2,324)
Identifiable intangible assets - adjustment	(100)
Total identifiable net assets - adjustment	(2,487)
Goodwill - adjustment	2,586
Total purchase price - adjustment	$ 99