GOODWILL AND INTANGIBLE ASSETS - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in the carrying amount of goodwill, by operating segment
Balance at the beginning of the period	$ 60,691	$ 63,970
Impairment	0	(3,279)	$ 0
Balance at the end of the period	60,691	60,691	63,970
International Telecom
Changes in the carrying amount of goodwill, by operating segment
Balance at the beginning of the period	24,326	24,326
Impairment	0	0
Balance at the end of the period	24,326	24,326	24,326
US Telecom
Changes in the carrying amount of goodwill, by operating segment
Balance at the beginning of the period	35,268	35,268
Impairment	0	0
Balance at the end of the period	35,268	35,268	35,268
Renewable Energy
Changes in the carrying amount of goodwill, by operating segment
Balance at the beginning of the period	0	3,279
Impairment	0	(3,279)
Balance at the end of the period	$ 0	$ 0	$ 3,279