SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment reporting
Number of reportable segments | segment	3
Revenue
Revenue	$ 103,300	$ 104,475
Depreciation and amortization	20,718	21,305
Non-cash stock-based compensation	1,301	1,576
Operating income (loss)	2,114	4,209
Segment Assets
Cash, Cash equivalents, and Investments	176,763		$ 192,229
Total current assets	261,144		275,765
Fixed assets, net	619,798		626,852
Goodwill	63,970		63,970
Total assets	1,162,830		1,107,304
Total current liabilities	141,317		140,650
Total debt	90,068		90,982
Capital Expenditures
Capital expenditures	17,764	51,892
Hurricane rebuild capital expenditures	123	30,851
Hurricane insurance proceeds		34,606
Wireless
Revenue
Revenue	41,613	50,548
Wireline
Revenue
Revenue	60,197	48,096
Renewable Energy
Revenue
Revenue	1,490	5,831
Corporate and Other
Revenue
Depreciation and amortization	1,489	1,347
Non-cash stock-based compensation	1,290	1,518
Operating income (loss)	(8,055)	(8,591)
Segment Assets
Cash, Cash equivalents, and Investments	64,300		78,043
Total current assets	58,246		83,107
Fixed assets, net	22,781		20,381
Total assets	172,714		181,789
Total current liabilities	35,002		38,827
Capital Expenditures
Capital expenditures	2,724	2,291
U.S. Telecom | Operating segments
Revenue
Revenue	21,493	28,499
Depreciation and amortization	5,598	6,513
Operating income (loss)	(3,506)	5,224
Segment Assets
Cash, Cash equivalents, and Investments	14,858		19,118
Total current assets	38,580		36,801
Fixed assets, net	75,004		78,102
Goodwill	35,269		35,269
Total assets	217,756		172,634
Total current liabilities	25,517		15,783
Capital Expenditures
Capital expenditures	3,075	4,751
U.S. Telecom | Operating segments | Wireless
Revenue
Revenue	20,437	27,401
U.S. Telecom | Operating segments | Wireline
Revenue
Revenue	1,056	1,098
International Telecom | Operating segments
Revenue
Revenue	80,317	70,145
Depreciation and amortization	13,015	11,671
Non-cash stock-based compensation	11	29
Operating income (loss)	13,878	5,640
Segment Assets
Cash, Cash equivalents, and Investments	40,731		32,390
Total current assets	89,785		75,304
Fixed assets, net	477,147		482,770
Goodwill	25,421		25,421
Total assets	648,736		622,454
Total current liabilities	78,649		82,575
Total debt	90,068		90,970
Capital Expenditures
Capital expenditures	11,356	43,996
Hurricane rebuild capital expenditures	100	30,900
Hurricane insurance proceeds		34,600
International Telecom | Operating segments | Wireless
Revenue
Revenue	21,176	23,147
International Telecom | Operating segments | Wireline
Revenue
Revenue	59,141	46,998
Renewable Energy | Operating segments
Revenue
Revenue	1,490	5,831
Depreciation and amortization	616	1,774
Non-cash stock-based compensation		29
Operating income (loss)	(203)	1,936
Segment Assets
Cash, Cash equivalents, and Investments	56,874		62,678
Total current assets	74,533		80,553
Fixed assets, net	44,866		45,599
Goodwill	3,280		3,280
Total assets	123,624		130,427
Total current liabilities	2,149		3,465
Total debt			$ 12
Capital Expenditures
Capital expenditures	609	854
Renewable Energy | Operating segments | Renewable Energy
Revenue
Revenue	$ 1,490	$ 5,831