SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Computation of basic and diluted earnings per share (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss attributable to ATN International, Inc. stockholders- Basic	$ (14,538)	$ (5,645)	$ (22,108)
Less: Preferred dividends	(4,942)	(4,856)	(1,962)
Net Loss attributable to ATN International, Inc. common stockholders- Diluted	$ (19,480)	$ (10,501)	$ (24,070)
Denominator:
Weighted-average shares outstanding- Basic	15,595	15,751	15,867
Weighted-average shares outstanding- Diluted	15,595	15,751	15,867