BUSINESS COMBINATIONS (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 254,001	$ 249,939
Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable	2,030
Materials and supplies	250
Equipment and property	3,393
Goodwill	2,304
Customer contracts	35,571
Other intangible assets	589
Current liabilities	(4,319)
Other assets and liabilities, net	(2,035)
Total consideration paid	37,783
Less: Contingent consideration liability	(2,745)
Total cash purchase price	$ 35,038