ACQUISITIONS AND DISPOSITIONS - Disposition - Sovernet (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Mar. 08, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets and liabilities disposed
Purchase of non-controlling interests			$ 2,026	$ 3,598
Loss on deconsolidation of subsidiary			529		$ 19,937
Impairment charges				11,425
Impairment of long-lived assets				3,600
Goodwill impairment			0	$ 7,492
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sovernet
Disposition
Cash proceeds	$ 20,900
Receivables, escrowed	3,000
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
Prepaid	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)
Loss	(2,387)
Purchase of non-controlling interests	700
Non-controlling interest book value	0
Loss on deconsolidation of subsidiary	500
Transaction-related charges			$ 600
Impairment charges		$ 11,100
Impairment of long-lived assets		3,600
Goodwill impairment		$ 7,500
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sovernet | Maximum
Disposition
Contingent consideration	$ 4,000