DISPOSITIONS AND PLATFORM INVESTMENTS - Disposition - Sovernet (Details) - USD ($) $ in Thousands		12 Months Ended
	Mar. 08, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets and liabilities disposed
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests		$ 4,504	$ 9,663	$ 2,026
Loss on deconsolidation of subsidiary				529
Sovernet | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disposition
Contingent consideration	$ 2,000
Fair value of contingent consideration				0
Total cash proceeds including working capital adjustments	25,926
Assets and liabilities disposed
Cash	1,821
Accounts receivable	1,696
Inventory	639
Prepayments and other current assets	1,034
Property, plant and equipment	25,294
Other assets	288
Accounts payable and accrued liabilities	(1,718)
Advance payments and deposits	(1,897)
Net assets disposed	27,157
Consideration less net assets disposed	(1,231)
Transaction costs	(1,156)
Gain	(2,387)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	700
Disposition Of Non Controlling Interest Book Value	0
Loss on deconsolidation of subsidiary	500
Disposal Group Related Costs				$ 600	$ 600
Maximum | Sovernet | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disposition
Contingent consideration	$ 4,000