ASSET PURCHASE - Purchase Price and Fair Value of Acquired Assets and Assumed Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Asset Acquisition [Line Items]
Property and equipment		$ 1,044	$ 2,348
Net assets acquired		$ 21,749	$ 0
GEOK
Asset Acquisition [Line Items]
Purchase price	$ 18,411
Transaction advisory fees and other acquisition costs	3,338
Total purchase price	21,749
Accounts receivable	8,589
Property and equipment	12,484
Intangible assets, net	3,642
Accrued liabilities	(110)
Deferred revenue	(2,856)
Net assets acquired	$ 21,749