GOODWILL AND INTANGIBLE ASSETS - Change In Carrying Amount Of Telecommunications Licenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in the carrying amount of the company's telecommunications licenses, by operating segment
Balance at the beginning of the period	$ 93,686
Balance at the end of the period	93,686	$ 93,686
Telecommunications Licenses
Telecommunications licenses
Impairment of intangible assets		0	$ 0
Changes in the carrying amount of the company's telecommunications licenses, by operating segment
Balance at the beginning of the period	93,686	95,952
Acquired licenses	0	485
Dispositions	0	(2,751)
Balance at the end of the period	93,686	93,686	95,952
Telecommunications Licenses | International Telecom
Changes in the carrying amount of the company's telecommunications licenses, by operating segment
Balance at the beginning of the period	23,347	23,347
Acquired licenses	0	0
Dispositions	0
Balance at the end of the period	23,347	23,347	23,347
Telecommunications Licenses | US Telecom
Changes in the carrying amount of the company's telecommunications licenses, by operating segment
Balance at the beginning of the period	70,339	72,605
Acquired licenses	0	485
Dispositions	0	(2,751)
Balance at the end of the period	$ 70,339	$ 70,339	$ 72,605