| Cover | Feb. 23, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 23, 2021 |
| Entity File Number | 001-12593 |
| Entity Registrant Name | ATN INTERNATIONAL, INC. |
| Entity Central Index Key | 0000879585 |
| Entity Tax Identification Number | 47-0728886 |
| Entity Incorporation, State or Country Code | DE |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $.01 per share |
| Trading Symbol | ATNI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
