XML 76 R61.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Schedule III: Real Estate and Accumulated Depreciation - Rollforward of Real Estate and Accumulated Deprecation (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
REAL ESTATE: |  |  |
Balance at beginning of period | $ 1,084,598 | $ 1,069,426 | $ 1,071,043
Changes during the period | 1,088,903 | 1,084,621 | 1,086,975
Assets sold | (14,186) | 0 | (11,921)
Assets written-off | (8,097) | (23) | (5,628)
Balance at end of period | 1,066,620 | 1,084,598 | 1,069,426
ACCUMULATED DEPRECIATION: |  |  |
Balance at beginning of period | 396,268 | 370,557 | 350,122
Depreciation expense | 28,137 | 25,734 | 26,063
Subtotal of accumulated depreciation | 424,405 | 396,291 | 376,185
Accumulated depreciation on assets sold | (405) | 0 | 0
Accumulated depreciation on assets written-off | (8,097) | (23) | (5,628)
Balance at end of period | 415,903 | 396,268 | 370,557
Land |  |  |
REAL ESTATE: |  |  |
Changes during the period | 0 | 0 | 0
Buildings and leasehold improvements |  |  |
REAL ESTATE: |  |  |
Changes during the period | 2,959 | 15,002 | 5,842
Development and construction in progress |  |  |
REAL ESTATE: |  |  |
Changes during the period | $ 1,346 | $ 193 | $ 10,090

X
- Definition SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Write-off Of Assets + References No definition available. + Details
Name: | alx_SECSchedule1228RealEstateCompaniesInvestmentInRealEstateAccumulatedDepreciationWriteOffOfAssets
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Real Estate Before Real Estate Sold And Written Off + References No definition available. + Details
Name: | alx_SECSchedule1228RealEstateCompaniesInvestmentInRealEstateRealEstateBeforeRealEstateSoldAndWrittenOff
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Column F)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase (decrease) in accumulated depreciation on real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of decrease to accumulated depreciation for real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_RealEstateCostOfRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, before accumulated depreciation, of real estate investment by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. Excludes real estate not held as investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Column E)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_RealEstateGrossAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ReconciliationOfCarryingAmountOfRealEstateInvestmentsRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of depreciation expense of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of write-down or reserve recognized in the income statement on real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 970 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 5)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479438/970-360-S99-1 + Details
Name: | us-gaap_SECScheduleIIIRealEstateWritedownOrReserveAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_LandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_BuildingImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_ConstructionInProgressMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |