Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 10, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2021
Entity File Number	001-12593
Entity Registrant Name	ATN INTERNATIONAL, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-0728886
Entity Address, Address Line One	500 Cummings Center
Entity Address, City or Town	Beverly
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01915
City Area Code	978
Local Phone Number	619-1300
Title of 12(b) Security	Common Stock, par value $.01 per share
Trading Symbol	ATNI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		15,921,222
Entity Central Index Key	0000879585
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false