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

Capacity Of Irrigation Water Supplied By Additional Watershed Lands

No definition available.

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

Facilities, Power Capacity

No definition available.

Name:	alex_FacilitiesPowerCapacity
Namespace Prefix:	alex_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	duration

Number Of Hydrologic Units

No definition available.

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

Number Of Hydrologic Units, Restored

No definition available.

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

Number Of Joint Ventures

No definition available.

Name:	alex_NumberOfJointVentures
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

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

Watershed Lands Owned

No definition available.

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

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
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

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

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.

No definition available.

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

Number of plaintiffs that have filed claims pertaining to a loss contingency.

No definition available.

Name:	us-gaap_LossContingencyNumberOfPlaintiffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=alex_KRSIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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