SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current deferred tax assets		$ 2,588
Current deferred tax liabilities		$ 213
Accounting Standards Update 2015-17 [Member] \| Reclassification to Noncurrent [Member]
Current deferred tax assets	$ 3,900
Current deferred tax liabilities	$ 200

Amount, after allocation of valuation allowances of deferred tax asset attributable to deductible differences and carryforwards, netted by jurisdiction and classified as current.

No definition available.

Name:	atni_DeferredTaxAssetsNetOfValuationAllowanceCurrent
Namespace Prefix:	atni_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant