Revenue Recognition - Impacts of adoption in the current period - CIS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income	$ 10,780	$ 10,909	$ 8,477	$ 22,494
Other comprehensive loss, net of tax	(2,509)	(543)	(3,402)	1,571
Comprehensive income	8,271	10,366	5,075	24,065
Less: Comprehensive income attributable to non-controlling interests	(3,564)	(5,026)	(6,816)	(9,751)
Comprehensive income (loss) attributable to ATN International, Inc.	4,707	$ 5,340	(1,741)	$ 14,314
ASU 2014-09 | Change
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income	395		813
Comprehensive income	395		813
Less: Comprehensive income attributable to non-controlling interests	(154)		(335)
Comprehensive income (loss) attributable to ATN International, Inc.	241		478
ASU 2014-09 | Under previous guidance
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income	10,385		7,664
Other comprehensive loss, net of tax	(2,509)		(3,402)
Comprehensive income	7,876		4,262
Less: Comprehensive income attributable to non-controlling interests	(3,410)		(6,481)
Comprehensive income (loss) attributable to ATN International, Inc.	$ 4,466		$ (2,219)