Name:	alex_AdditionalWatershedLandsAccessibleByLicenses
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Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

The approximate percentage of irrigation water used by HC and S over the last ten years provided by the West Maui irrigation system.

No definition available.

Name:	alex_ApproximatePercentageOfIrrigationWaterProvidedByWestMauiIrrigationSystem
Namespace Prefix:	alex_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The capacity of irrigation water used by HC and S supplied by the additional watershed lands over the last ten years.

No definition available.

Name:	alex_CapacityOfIrrigationWaterSuppliedByAdditionalWatershedLands
Namespace Prefix:	alex_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Loss Contingency, Noncompliant Boilers, Number

No definition available.

Name:	alex_LossContingencyNoncompliantBoilersNumber
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Loss Contingency, Non-compliant Period

No definition available.

Name:	alex_LossContingencyNoncompliantPeriod
Namespace Prefix:	alex_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of organizations that filed a petition with the Water Commission to establish IIFS.

No definition available.

Name:	alex_NumberOfOrganizationsThatFiledPetitionToEstablishIifs
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of petitions on which the Water Commission to action, which resulted in some quantity of water being returned to the streams rather than being utilized for irrigation purposes, as per the IIFS request.

No definition available.

Name:	alex_NumberOfPetitionsOnWhichWaterCommissionTookAction
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of streams for which interim instream flow standards (IIFS) was requested via petitions filed by a third party to the Commission on Water Resource Management of the state of Hawaii.

No definition available.

Name:	alex_NumberOfStreamsForWhichIifsWasRequested
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number of Units in Real Estate Property, Pre-Sold

No definition available.

Name:	alex_NumberofUnitsinRealEstatePropertyPreSold
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of water licenses held by the entity, which provides access to another 30,000 acres owned by the State of Hawaii in East Maui. All of these licenses were extended as revocable permits that are renewed annually.

No definition available.

Name:	alex_NumberOfWaterLicensesHeldAndExtendedAsRevocablePermits
Namespace Prefix:	alex_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Period provided by the irrigation system for water use.

No definition available.

Name:	alex_PeriodProvidedByIrrigationSystem
Namespace Prefix:	alex_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of acres of watershed lands in East Maui owned by the entity.

No definition available.

Name:	alex_WatershedLandsInEastMauiOwned
Namespace Prefix:	alex_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

This element represents the carrying value of a short-term real estate loan to finance building costs. The funds are disbursed as needed or in accordance with a prearranged plan; generally, a portion of the funds is disbursed at inception and the remainder as construction progresses. The money is repaid on completion of the project, usually from the proceeds of a mortgage loan. The rate is normally higher than the prime rate, and there is usually an origination fee. The effective yield on these loans tends to be high, and the lender has a security interest in the real property. Note that there are separate concepts for the current and noncurrent portions of long-term construction loans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(a)(1))

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20

-Article 5

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

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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

The estimated maximum amount of possible loss from the contingency.

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

The number of units in a real estate property owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfUnitsInRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_PaymentGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=alex_LongTermWaterLeaseRequestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=alex_PerformanceAndCustomsBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=alex_PetitionsFiledRequestingIifsInEastMauiStreamsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=alex_PetitionsFiledRequestingIifsInWestMauiStreamsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RegulatoryAgencyAxis=alex_EnvironmentalProtectionAgencyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RegulatoryAgencyAxis=alex_HawaiiStateDepartmentofHealthMember
Namespace Prefix:
Data Type:	na
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