SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment reporting
Number of reportable segments | segment			3
Revenue
Revenue	$ 117,788	$ 123,245	$ 222,263	$ 251,360
Depreciation and amortization	21,913	22,254	43,217	44,747
Non-cash stock-based compensation	2,103	2,098	3,679	3,786
Operating income (loss)	15,753	15,803	19,962	33,556
Segment Assets
Cash, Cash equivalents, and Investments	168,702		168,702		$ 215,032
Total current assets	264,313		264,313		342,928
Fixed assets, net	702,968		702,968		643,146
Goodwill	63,970		63,970		63,970
Total assets	1,188,999		1,188,999		1,205,605
Total current liabilities	157,390		157,390		161,705
Total debt	151,001		151,001		155,792
Capital Expenditures
Capital expenditures			107,248	78,559
Hurricane rebuild capital expenditures			66,654
Hurricane insurance proceeds			34,606
Wireless
Revenue
Revenue	50,496	56,546	101,043	115,471
Wireline
Revenue
Revenue	61,269	61,802	109,365	125,960
Renewable Energy
Revenue
Revenue	6,023	4,897	11,855	9,929
Corporate and Other
Revenue
Depreciation and amortization	1,385	1,044	2,731	2,416
Non-cash stock-based compensation	2,054	2,061	3,574	3,591
Operating income (loss)	(9,586)	(8,955)	(18,177)	(17,955)
Segment Assets
Cash, Cash equivalents, and Investments	90,176		90,176		76,627
Total current assets	105,220		105,220		93,497
Fixed assets, net	17,657		17,657		17,752
Total assets	197,503		197,503		184,050
Total current liabilities	20,910		20,910		13,816
Capital Expenditures
Capital expenditures			3,074	3,293
U.S. Telecom | Operating segments
Revenue
Revenue	30,284	36,978	58,783	80,771
Depreciation and amortization	6,835	6,246	13,348	12,797
Operating income (loss)	7,841	13,147	13,065	28,533
Segment Assets
Cash, Cash equivalents, and Investments	16,241		16,241		19,585
Total current assets	43,413		43,413		40,975
Fixed assets, net	92,435		92,435		99,462
Goodwill	35,269		35,269		35,269
Total assets	195,587		195,587		200,142
Total current liabilities	44,618		44,618		41,248
Capital Expenditures
Capital expenditures			7,266	12,602
U.S. Telecom | Operating segments | Wireless
Revenue
Revenue	28,582	34,921	55,983	72,623
U.S. Telecom | Operating segments | Wireline
Revenue
Revenue	1,702	2,057	2,800	8,148
International Telecom segment | Operating segments
Revenue
Revenue	81,481	81,370	151,625	160,660
Depreciation and amortization	11,794	13,134	23,465	26,250
Non-cash stock-based compensation	20	8	48	138
Operating income (loss)	15,571	10,765	21,211	20,691
Segment Assets
Cash, Cash equivalents, and Investments	49,882		49,882		110,700
Total current assets	97,603		97,603		190,396
Fixed assets, net	442,854		442,854		367,485
Goodwill	25,421		25,421		25,421
Total assets	611,654		611,654		629,007
Total current liabilities	79,484		79,484		91,887
Total debt	92,774		92,774		94,577
Capital Expenditures
Capital expenditures			95,520	37,129
International Telecom segment | Operating segments | Wireless
Revenue
Revenue	21,914	21,625	45,060	42,848
International Telecom segment | Operating segments | Wireline
Revenue
Revenue	59,567	59,745	106,565	117,812
Renewable Energy | Operating segments
Revenue
Revenue	6,023	4,897	11,855	9,929
Depreciation and amortization	1,899	1,830	3,673	3,284
Non-cash stock-based compensation	29	29	57	57
Operating income (loss)	1,927	846	3,863	2,287
Segment Assets
Cash, Cash equivalents, and Investments	12,403		12,403		8,120
Total current assets	18,077		18,077		18,060
Fixed assets, net	150,022		150,022		158,447
Goodwill	3,280		3,280		3,280
Total assets	184,255		184,255		192,406
Total current liabilities	12,378		12,378		14,754
Total debt	58,227		58,227		$ 61,215
Capital Expenditures
Capital expenditures			1,388	25,535
Renewable Energy | Operating segments | Renewable Energy
Revenue
Revenue	$ 6,023	$ 4,897	$ 11,855	$ 9,929