XML 73 R56.htm IDEA: XBRL DOCUMENT
v3.10.0.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Jan. 01, 2018 | Jan. 01, 2017
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Equity investments with readily determinable fair values | $ 300 |  |  |  | $ 600 |  |  |  | $ 300 | $ 600 |  |  |
Additional paid-in capital | 181,778 |  |  |  | 167,973 |  |  |  | 181,778 | 167,973 |  |  |
Accumulated other comprehensive income | (1,609) |  |  |  | 3,746 |  |  |  | (1,609) | 3,746 |  |  |
Retained earnings | 563,593 |  |  |  | 552,948 |  |  |  | 563,593 | 552,948 |  |  |
Net cash provided by operating activities |  |  |  |  |  |  |  |  | 115,865 | 145,725 | $ 111,656 |  |
Net cash used in investing activities |  |  |  |  |  |  |  |  | (87,319) | (172,318) | (296,580) |  |
Net cash used in financing activities |  |  |  |  |  |  |  |  | (55,230) | (42,101) | 75,334 |  |
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents |  |  |  |  |  |  |  |  | (299) | 226 | (626) |  |
Net change in cash, cash equivalents, and restricted cash |  |  |  |  |  |  |  |  | (26,983) | (68,468) | (110,216) |  |
Total cash, cash equivalents, and restricted cash, beginning of period |  |  |  | $ 219,890 |  |  |  | $ 288,358 | 219,890 | 288,358 | 398,574 |  |
Total cash, cash equivalents, and restricted cash, end of period | 192,907 |  |  |  | 219,890 |  |  |  | 192,907 | 219,890 | 288,358 |  |
Valuation allowance | 31,442 |  |  |  | 35,829 |  |  |  | 31,442 | 35,829 |  |  |
Restricted cash | 1,071 |  |  |  | 833 |  |  |  | 1,071 | 833 |  |  |
Operating Expenses | 97,488 | $ 90,395 | $ 102,035 | 100,266 | 66,387 | $ 141,697 | $ 107,442 | 110,359 | 390,184 | 425,885 | 405,733 |  |
ASU 2016-01 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Equity investments that do not have readily determinable fair values |  |  |  |  |  |  |  |  |  |  |  | $ 20,100 |
Equity investments with readily determinable fair values |  |  |  |  |  |  |  |  |  |  |  | 600 |
ASU 2018-15 | Early Adoption |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Capitalized implementation costs | 600 |  |  |  |  |  |  |  | 600 |  |  |  |
Amortization of implementation costs | $ 0 |  |  |  |  |  |  |  |  |  |  |  |
Change | Accounting Standards Update 2016-15 and 2018-18 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Net cash provided by operating activities |  |  |  |  |  |  |  |  |  | (5,525) |  |  |
Net cash used in investing activities |  |  |  |  |  |  |  |  |  |  | 12,108 |  |
Net cash used in financing activities |  |  |  |  |  |  |  |  |  | (1,178) |  |  |
Net change in cash, cash equivalents, and restricted cash |  |  |  |  |  |  |  |  |  | (6,703) | 12,108 |  |
Total cash, cash equivalents, and restricted cash, beginning of period |  |  |  | 11,934 |  |  |  | 18,637 | 11,934 | 18,637 | 6,529 |  |
Total cash, cash equivalents, and restricted cash, end of period |  |  |  |  | 11,934 |  |  |  |  | 11,934 | 18,637 |  |
Change | ASU 2017-07 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Expenses |  |  |  |  |  |  |  |  |  | 200 | (1,400) |  |
Other Income |  |  |  |  |  |  |  |  |  | 200 | (1,400) |  |
Previously Reported | Accounting Standards Update 2016-15 and 2018-18 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Net cash provided by operating activities |  |  |  |  |  |  |  |  |  | 145,725 | 111,656 |  |
Net cash used in investing activities |  |  |  |  |  |  |  |  |  | (166,793) | (308,688) |  |
Net cash used in financing activities |  |  |  |  |  |  |  |  |  | (40,923) | 75,334 |  |
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents |  |  |  |  |  |  |  |  |  | 226 | (626) |  |
Net change in cash, cash equivalents, and restricted cash |  |  |  |  |  |  |  |  |  | (61,765) | (122,324) |  |
Total cash, cash equivalents, and restricted cash, beginning of period |  |  |  | $ 207,956 |  |  |  | $ 269,721 | $ 207,956 | 269,721 | 392,045 |  |
Total cash, cash equivalents, and restricted cash, end of period |  |  |  |  | 207,956 |  |  |  |  | 207,956 | $ 269,721 |  |
Adjustment | ASU 2016-01 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated other comprehensive income |  |  |  |  |  |  |  |  |  |  |  | (200) |
Retained earnings |  |  |  |  |  |  |  |  |  |  |  | $ 200 |
Adjustment | ASU 2016-09 |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Additional paid-in capital |  |  |  |  |  |  |  |  |  |  |  |  | $ (300)
Retained earnings |  |  |  |  |  |  |  |  |  |  |  |  | $ 300
Adjustment | ASU 2018-02 | Early Adoption |  |  |  |  |  |  |  |  |  |  |  |  |
Recent accounting pronouncements |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated other comprehensive income |  |  |  |  | (800) |  |  |  |  | (800) |  |  |
Retained earnings |  |  |  |  | 800 |  |  |  |  | 800 |  |  |
Valuation allowance |  |  |  |  | $ 800 |  |  |  |  | $ 800 |  |  |

X
- Definition Amount, before accumulated amortization, of capitalized implementation cost from hosting arrangement that is service contract. + References No definition available. + Details
Name: | atni_HostingArrangementServiceContractImplementationCostCapitalizedBeforeAccumulatedAmortization
Namespace Prefix: | atni_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of amortization expense for capitalized implementation cost from hosting arrangement that is service contract. + References No definition available. + Details
Name: | atni_HostingArrangementServiceContractImplementationCostExpenseAmortization
Namespace Prefix: | atni_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e681-108580 + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Value received from shareholders in common stock-related transactions that are in excess of par value or stated value and amounts received from other stock-related transactions. Includes only common stock transactions (excludes preferred stock transactions). May be called contributed capital, capital in excess of par, capital surplus, or paid-in capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AdditionalPaidInCapitalCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 + Details
Name: | us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 230 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585 + Details
Name: | us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase (decrease) from effect of exchange rate changes on cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; held in foreign currencies. Excludes amounts for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 230 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906 + Details
Name: | us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 321 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117539-209714 + Details
Name: | us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInFinancingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInInvestingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInOperatingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense. + References No definition available. + Details
Name: | us-gaap_OperatingExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of revenue and income classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.4) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 + Details
Name: | us-gaap_OtherIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cumulative amount of the reporting entity's undistributed earnings or deficit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(23)(a)(4)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=atni_AccountingStandardsUpdate201815Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_NewAccountingPronouncementEarlyAdoptionAxis=us-gaap_AdjustmentsForNewAccountingPrincipleEarlyAdoptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RestatementAxis=srt_RestatementAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=atni_AccountingStandardsUpdate201615And201818Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201707Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RestatementAxis=srt_ScenarioPreviouslyReportedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201609Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=atni_AccountingStandardsUpdate201802Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |