SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment reporting
Number of reportable segments | segment			3
Revenue
Revenue	$ 111,739	$ 115,616	$ 331,743	$ 326,637
Depreciation and amortization	21,580	22,603	66,089	64,870
Non-cash stock-based compensation	1,887	1,548	4,608	4,881
Operating income (loss)	9,557	10,248	23,879	15,117
Segment Assets
Cash, Cash equivalents, and Investments	135,556		135,556		$ 161,703
Total current assets	225,584		225,584		228,723
Fixed assets, net	589,428		589,428		605,581
Goodwill	60,691		60,691		60,691
Total assets	1,113,414		1,113,414		1,130,726
Total current liabilities	132,862		132,862		119,669
Total debt	83,723		83,723		86,426
Capital Expenditures
Capital expenditures			50,662	49,486
Communication services
Revenue
Revenue	108,721	112,840	322,865	318,473
Mobility
Revenue
Revenue	23,838	23,965	67,807	70,861
Fixed
Revenue
Revenue	62,783	60,149	187,601	176,810
Carrier services
Revenue
Revenue	21,703	28,391	66,171	69,790
Other
Revenue
Revenue	397	335	1,286	1,012
Other
Revenue
Revenue	3,018	2,776	8,878	8,164
Renewable Energy
Revenue
Revenue	1,177	1,438	3,373	4,376
Managed Services
Revenue
Revenue	1,447	1,338	5,111	3,788
Construction
Revenue
Revenue	394		394
Corporate and Other
Revenue
Depreciation and amortization	1,689	1,728	5,048	4,973
Non-cash stock-based compensation	1,792	1,263	4,391	4,575
Operating income (loss)	(8,587)	(7,817)	(25,306)	(25,862)
Segment Assets
Cash, Cash equivalents, and Investments	20,302		20,302		55,284
Total current assets	15,978		15,978		55,485
Fixed assets, net	14,335		14,335		21,453
Total assets	144,062		144,062		184,419
Total current liabilities	23,801		23,801		14,375
Capital Expenditures
Capital expenditures			2,853	5,611
International Telecom | Operating segments
Revenue
Revenue	82,465	81,285	244,813	241,461
Depreciation and amortization	13,671	14,089	42,120	40,709
Non-cash stock-based compensation	29	285	20	306
Operating income (loss)	16,024	10,867	44,119	35,802
Segment Assets
Cash, Cash equivalents, and Investments	67,701		67,701		43,125
Total current assets	124,515		124,515		91,497
Fixed assets, net	452,303		452,303		466,523
Goodwill	25,421		25,421		25,421
Total assets	664,307		664,307		647,228
Total current liabilities	71,254		71,254		77,644
Total debt	83,723		83,723		86,426
Capital Expenditures
Capital expenditures			28,439	8,533
International Telecom | Operating segments | Communication services
Revenue
Revenue	81,018	79,947	239,702	237,673
International Telecom | Operating segments | Mobility
Revenue
Revenue	21,406	21,364	60,604	62,766
International Telecom | Operating segments | Fixed
Revenue
Revenue	57,364	55,845	172,420	166,925
International Telecom | Operating segments | Carrier services
Revenue
Revenue	1,851	2,403	5,392	6,970
International Telecom | Operating segments | Other
Revenue
Revenue	397	335	1,286	1,012
International Telecom | Operating segments | Other
Revenue
Revenue	1,447	1,338	5,111	3,788
International Telecom | Operating segments | Managed Services
Revenue
Revenue	1,447	1,338	5,111	3,788
US Telecom | Operating segments
Revenue
Revenue	28,097	32,893	83,557	80,800
Depreciation and amortization	5,729	5,770	17,331	16,919
Operating income (loss)	2,218	7,912	6,241	5,927
Segment Assets
Cash, Cash equivalents, and Investments	25,177		25,177		38,240
Total current assets	59,801		59,801		54,207
Fixed assets, net	77,017		77,017		69,184
Goodwill	35,270		35,270		35,270
Total assets	233,288		233,288		222,356
Total current liabilities	36,898		36,898		24,905
Capital Expenditures
Capital expenditures			17,254	33,159
US Telecom | Operating segments | Communication services
Revenue
Revenue	27,703	32,893	83,163	80,800
US Telecom | Operating segments | Mobility
Revenue
Revenue	2,432	2,601	7,203	8,095
US Telecom | Operating segments | Fixed
Revenue
Revenue	5,419	4,304	15,181	9,885
US Telecom | Operating segments | Carrier services
Revenue
Revenue	19,852	25,988	60,779	62,820
US Telecom | Operating segments | Other
Revenue
Revenue	394		394
US Telecom | Operating segments | Construction
Revenue
Revenue	394		394
Renewable Energy | Operating segments
Revenue
Revenue	1,177	1,438	3,373	4,376
Depreciation and amortization	491	1,016	1,590	2,269
Non-cash stock-based compensation	66		197
Operating income (loss)	(98)	(714)	(1,175)	(750)
Segment Assets
Cash, Cash equivalents, and Investments	22,376		22,376		25,054
Total current assets	25,290		25,290		27,534
Fixed assets, net	45,773		45,773		48,421
Total assets	71,757		71,757		76,723
Total current liabilities	909		909		$ 2,745
Capital Expenditures
Capital expenditures			2,116	2,183
Renewable Energy | Operating segments | Other
Revenue
Revenue	1,177	1,438	3,373	4,376
Renewable Energy | Operating segments | Renewable Energy
Revenue
Revenue	$ 1,177	$ 1,438	$ 3,373	$ 4,376