Represents the minimum amount for which the reporting entity is required enter into or obtain an interest rate hedge.

No definition available.

Name:	alsk_DebtInstrumentCovenantsMinimumBorrowing
Namespace Prefix:	alsk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the London Interbank Offered Rate associated with a debt instrument.

+ References

No definition available.

+ Details

Name:	alsk_DebtInstrumentLondonInterbankOfferedRate
Namespace Prefix:	alsk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of accrued interest on the debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	alsk_DebtInstrumentRepurchaseAmountAccruedInterest
Namespace Prefix:	alsk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the weighted average life of a senior credit facility.

+ References

No definition available.

+ Details

Name:	alsk_WeightedAverageLifeOfSeniorCreditFacility
Namespace Prefix:	alsk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ 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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

+ References

No definition available.

+ Details

Name:	us-gaap_GainLossOnRepurchaseOfDebtInstrument
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=alsk_The2017SeniorCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=alsk_TermA1FacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=alsk_TermA2FacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=alsk_RevolvingCreditFacilityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=alsk_SixPointTwentyFivePercentConvertibleNotesDue2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=alsk_SixPointTwentyFivePercentConvertibleNotesDue2018RepurchasedUtilizingRestrictedCashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=alsk_SixPointTwentyFivePercentConvertibleNotesDue2018RepurchasedUtilizingCashOnHandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 7 - Long-term Obligations (Details Textual) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended	21 Months Ended	30 Months Ended	42 Months Ended
	May 01, 2018	Dec. 31, 2021	Sep. 30, 2018	Mar. 31, 2021	Dec. 31, 2022	Mar. 31, 2020	Mar. 31, 2021	Dec. 31, 2017
The 2017 Senior Credit Facility [Member]
Debt Instrument Covenants, Minimum Borrowing			$ 90,000
Weighted Average Life of Senior Credit Facility			2 years
The 2017 Senior Credit Facility [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity			$ 15,000
The 2017 Senior Credit Facility [Member] \| Term A-1 Facility [Member]
Debt Instrument, Face Amount			$ 120,000
Debt Instrument, Maturity Date			Mar. 13, 2022
The 2017 Senior Credit Facility [Member] \| Term A-1 Facility [Member] \| Scenario, Forecast [Member]
Debt Instrument, Periodic Payment, Principal		$ 4,000		$ 2,250		$ 1,500
The 2017 Senior Credit Facility [Member] \| Term A-1 Facility [Member] \| Minimum [Member]
Debt Instrument, London Interbank Offered Rate			1.00%
The 2017 Senior Credit Facility [Member] \| Term A-1 Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			5.00%
The 2017 Senior Credit Facility [Member] \| Term A-2 Facility [Member]
Debt Instrument, Maturity Date			Mar. 13, 2023
The 2017 Senior Credit Facility [Member] \| Term A-2 Facility [Member] \| Scenario, Forecast [Member]
Debt Instrument, Periodic Payment, Principal					$ 600		$ 150
The 2017 Senior Credit Facility [Member] \| Term A-2 Facility [Member] \| Minimum [Member]
Debt Instrument, London Interbank Offered Rate			1.00%
The 2017 Senior Credit Facility [Member] \| Term A-2 Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Face Amount			$ 60,000
Debt Instrument, Basis Spread on Variable Rate			7.00%
The 2017 Senior Credit Facility [Member] \| Revolving Credit Facility Loan [Member] \| Minimum [Member]
Debt Instrument, London Interbank Offered Rate			1.00%
The 2017 Senior Credit Facility [Member] \| Revolving Credit Facility Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			5.00%
6.25% Convertible Notes Due 2018 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.25%		6.25%					6.25%
Debt Instrument, Repurchase Amount	$ 10,358
Debt Instrument, Repurchased Face Amount	10,044
Debt Instrument, Repurchase Amount, Accrued Interest	314
Gain (Loss) on Repurchase of Debt Instrument	0
6.25% Convertible Notes Due 2018 Repurchased Utilizing Restricted Cash [Member]
Debt Instrument, Repurchase Amount	10,044
6.25% Convertible Notes Due 2018 Repurchased Utilizing Cash On Hand [Member]
Debt Instrument, Repurchase Amount	$ 314