ACQUISITIONS AND DISPOSITIONS - Unaudited pro forma operating results (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
ACQUISITIONS AND DISPOSITIONS
Amount of pre-Close debt, and associated interest removed from pro forma results	$ 164,600
Transaction debt included in pro forma results	283,000
Revenue	602,707	$ 455,444	$ 438,722
Net income (loss) attributable to ATN International, Inc. Stockholders	$ (22,108)	$ (14,122)	$ (10,806)
Earnings Per Share
Basic (in dollars per share)	$ (1.52)	$ (0.89)	$ (0.68)
Diluted (in dollars per share)	$ (1.52)	$ (0.89)	$ (0.68)
Pro Forma
Revenue	$ 738,472	$ 696,013
Net income (loss) attributable to ATN International, Inc. Stockholders	(20,022)	(40,186)
Unaudited pro forma adjustments	$ 2,100	26,100
Transaction related costs		$ 27,400
Earnings Per Share
Basic (in dollars per share)	$ (1.26)	$ (2.52)
Diluted (in dollars per share)	$ (1.26)	$ (2.52)