Note 12 - Stock Incentive Plans (Details Textual) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019 USD ($)	Jun. 30, 2019
Restricted Stock Units (RSUs) [Member] \| Share-based Compensation Awards Issued in 2018, Vesting Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share-based Payment Arrangement, Accelerated Cost	$ 112
Performance Share Units [Member] \| Awards Granted in 2018 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Equal Installments		3
Share Based Payment Arrangement, Modification Expense	$ 165

Represents the number of equal installments over which share-based awards will vest.

No definition available.

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Namespace Prefix:	alsk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of additional cost recognized for award under share-based payment arrangement from occurrence of event modifying recognition of cost.

+ References

No definition available.

+ Details

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Namespace Prefix:	alsk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of additional cost recognized for award under share-based payment arrangement from occurrence of event accelerating recognition of cost.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Data Type:	na
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- Details

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