IMPACT OF HURRICANES IRMA AND MARIA (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
IMPACT OF THE HURRICANES IRMA AND MARIA
Revenue	$ 123,702	$ 111,739	$ 109,098	$ 110,905	$ 112,085	$ 115,616	$ 107,721	$ 103,300	$ 455,444	$ 438,722	$ 451,207
Payment for network repairs and resiliency enhancements										123	80,152
HURRICANES IRMA AND MARIA
IMPACT OF THE HURRICANES IRMA AND MARIA
Payment for network repairs and resiliency enhancements										$ 100	80,200
HURRICANES IRMA AND MARIA | Universal Service Fund programs
IMPACT OF THE HURRICANES IRMA AND MARIA
Revenue											$ 15,500