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LONG-TERM DEBT (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended | 0 Months Ended | 16 Months Ended | 0 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | May 18, 2012 item | Sep. 20, 2013 | Nov. 14, 2013 | Jun. 17, 2013 | Dec. 19, 2014 | Jun. 30, 2013
Ahana Renewables |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Long-term debt | $ 38.9 atni_LongTermDebtNoncurrentCarryingAmount / us-gaap_BusinessAcquisitionAxis = atni_AhanaRenewablesLlcMember |  |  |  |  |  |  |
Ahana Renewables | Public Service Electric & Gas |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Effective interest rate (as a percent) | 11.30%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_BusinessAcquisitionAxis = atni_AhanaRenewablesLlcMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = atni_PublicServiceElectricAndGasMember |  |  |  |  |  |  |
Minimum | Ahana Renewables |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Effective interest rate (as a percent) | 4.50%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_BusinessAcquisitionAxis = atni_AhanaRenewablesLlcMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |  |  |
Maximum | Ahana Renewables |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Effective interest rate (as a percent) | 6.00%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_BusinessAcquisitionAxis = atni_AhanaRenewablesLlcMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |  |
Amended Credit Facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Borrowings | 0 us-gaap_ProceedsFromLinesOfCredit / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember |  |  |  |  |  |  |
Term loans |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Number of loans repaid in full |  |  |  | 2 atni_LineOfCreditFacilityNumberOfLoansRepaid / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember |  |  |  |
Interest expenses |  | 4.7 us-gaap_InterestExpenseDebt / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember |  |  |  |  |  |
Term loans | Credit facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  | 275.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember |  |  |  |  |
Number of term loans |  |  | 2 atni_LineOfCreditFacilityMaximumBorrowingCapacityNumberOfLoans / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember |  |  |  |  |
Maximum aggregate additional borrowings subject to lender approval |  |  | 100.0 atni_DebtInstrumentIncreaseMaximumAdditionalBorrowingsSubjectToLenderApproval / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember |  |  |  |  |
Term loans | Credit facility | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  |  |  | LIBOR |  |  |  |
Term loans | Credit facility | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  |  |  | Base Rate |  |  |  |
Term loans | Credit facility | One-week LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  |  |  | one-week LIBOR |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_VariableRateAxis = atni_DebtInstrumentVariableRateBaseOneWeekLIBORMember |  |  |  |
Term loans | Credit facility | One-month LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  |  |  | one-month LIBOR |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_VariableRateAxis = atni_DebtInstrumentVariableRateBaseOneMonthLIBORMember |  |  |  |
Term loans | Credit facility | Prime Rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  |  |  | Prime Rate |  |  |  |
Term loans | Credit facility | Minimum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |
Term loans | Credit facility | Minimum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |
Term loans | Credit facility | Maximum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 4.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |
Term loans | Credit facility | Maximum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  |  |  | 3.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_TermLoanMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |
Revolving credit facility | Credit facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  | 100.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember |  |  |  |  |
Revolving credit facility | Credit facility | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  | LIBOR |  |  |  |  |  |
Revolving credit facility | Credit facility | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  | Base Rate |  |  |  |  |  |
Revolving credit facility | Credit facility | Minimum |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Commitment fee (as a percent) |  | 0.25%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |  |
Revolving credit facility | Credit facility | Minimum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |  |  |
Revolving credit facility | Credit facility | Minimum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |
Revolving credit facility | Credit facility | Maximum |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Commitment fee (as a percent) |  | 0.50%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |
Revolving credit facility | Credit facility | Maximum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 3.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |  |  |
Revolving credit facility | Credit facility | Maximum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 2.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 225.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember |
Revolving credit facility | Amended Credit Facility | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | LIBOR |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | base rate |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Minimum |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Commitment fee (as a percent) | 0.175%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Minimum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Minimum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Maximum |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Commitment fee (as a percent) | 0.25%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Maximum | LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 1.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |  |  |  |  |
Revolving credit facility | Amended Credit Facility | Maximum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 0.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |  |
Swingline sub-facility | Credit facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  | 10.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember |  |  |  |  |
Swingline sub-facility | Credit facility | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis |  | Base Rate |  |  |  |  |  |
Swingline sub-facility | Credit facility | Minimum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |
Swingline sub-facility | Credit facility | Maximum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) |  | 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 10.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember |
Swingline sub-facility | Amended Credit Facility | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | base rate |  |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility | One-week LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | one-week LIBOR |  |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility | One-month LIBOR |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | one-month LIBOR |  |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility | Prime Rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | prime rate |  |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility | Federal Funds Effective Rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Description of variable rate basis | federal funds effective rate |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember / us-gaap_VariableRateAxis = us-gaap_FederalFundsEffectiveSwapRateMember |  |  |  |  |  |  |
Swingline sub-facility | Amended Credit Facility | Minimum | Base rate |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Basis spread on variable rate (as a percent) | 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = atni_SwinglineSubFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_VariableRateAxis = us-gaap_BaseRateMember |  |  |  |  |  |  |
Letter of credit sub-facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Outstanding letters of credit | 10.6 us-gaap_LettersOfCreditOutstandingAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember |  |  |  |  |  |  |
Letter of credit sub-facility | Alltel Mobility Funds |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Termination of facility |  |  |  |  | 19.9 us-gaap_ExtinguishmentOfDebtAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_AlltelMobilityFundsMember |  |  |
Letter of credit sub-facility | Universal Service Administrative Company |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Outstanding letters of credit |  |  |  |  |  |  |  | 29.8 us-gaap_LettersOfCreditOutstandingAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_UniversalServiceAdministrativeCompanyMember
Termination of facility |  |  |  |  | 19.9 us-gaap_ExtinguishmentOfDebtAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_UniversalServiceAdministrativeCompanyMember |  |  |
Letter of credit sub-facility | Credit facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Amount of pending awards of mobility fund grants |  |  |  |  |  | 68.8 atni_AmountOfPendingAwardsToBeSecuredAgainstIssuanceOfDebtInstrument / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember |  |
Letter of credit sub-facility | Credit facility | Universal Service Administrative Company |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Outstanding letters of credit |  |  |  |  |  | 29.8 us-gaap_LettersOfCreditOutstandingAmount / us-gaap_CreditFacilityAxis = atni_CreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_UniversalServiceAdministrativeCompanyMember |  |
Letter of credit sub-facility | Amended Credit Facility |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity | 55.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember |  |  |  |  |  | 10.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember |
Commitment fee (as a percent) |  |  |  |  |  | 1.75%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember |  |
Letter of credit sub-facility | Amended Credit Facility | Alltel Mobility Funds |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  |  | 25.0 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_AlltelMobilityFundsMember |
Amount of pending awards of mobility fund grants |  |  |  |  |  | 68.8 atni_AmountOfPendingAwardsToBeSecuredAgainstIssuanceOfDebtInstrument / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_AlltelMobilityFundsMember |  |
Letter of credit sub-facility | Amended Credit Facility | Universal Service Administrative Company |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |
Outstanding letters of credit |  | $ 9.9 us-gaap_LettersOfCreditOutstandingAmount / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_UniversalServiceAdministrativeCompanyMember |  |  |  | $ 29.8 us-gaap_LettersOfCreditOutstandingAmount / us-gaap_CreditFacilityAxis = atni_AmendmentToCreditFacilityMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LetterOfCreditMember / atni_TypeOfMobilityFundAxis = atni_UniversalServiceAdministrativeCompanyMember |  |

X
- Definition Represents the amount of pending awards of mobility fund grants to be secured against the issuance of debt instrument. + References No definition available. + Details
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Period Type: | duration

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- Definition Represents the maximum aggregate amount of additional borrowings available to the entity, subject to lender's approval. + References No definition available. + Details
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Namespace Prefix: | atni_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Represents the number of term loans in which credit facility will be provided. + References No definition available. + Details
Name: | atni_LineOfCreditFacilityMaximumBorrowingCapacityNumberOfLoans
Namespace Prefix: | atni_
Data Type: | xbrli:integerItemType
Balance Type: | na
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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