XML 48 R36.htm IDEA: XBRL DOCUMENT
v3.26.1

Related Party Transactions - Narrative (Details) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2026 USD ($) | Jun. 30, 2025 USD ($) | Jun. 30, 2026 USD ($) $ / ft² | Jun. 30, 2025 USD ($) | Dec. 31, 2025 USD ($)
Related Party Transaction [Line Items] |  |  |  |  |
Fees to related party | $ 5,638,000 | $ 2,600,000 | $ 7,712,000 | $ 5,191,000 |
Development fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Fees to related party | 79,000 | 207,000 | 144,000 | 626,000 |
Leasing fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Fees to related party | 492,000 | 229,000 | 522,000 | 242,000 |
Property management, cleaning, engineering, parking and security fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Fees to related party | 2,012,000 | $ 1,464,000 | 3,291,000 | $ 2,923,000 |
Related Party |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Management fee agreement value |  |  | 2,800,000 |  |
Other liabilities | 1,044,000 |  | $ 1,044,000 |  | $ 134,000
Related Party | Rego Park I property |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Payments for commissions | 2,355,000 |  |  |  |
Related Party | Development fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Development fee as percentage of development costs |  |  | 6.00% |  |
Other liabilities | 79,000 |  | $ 79,000 |  | 34,000
Related Party | Leasing fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Lease fee percentage of rent one to ten years |  |  | 3.00% |  |
Lease fee percentage of rent eleven to twenty years |  |  | 2.00% |  |
Lease fee percentage of rent twenty first to thirty years |  |  | 1.00% |  |
Percentage of third-party lease commission |  |  | 33.333% |  |
Percentage commissions on sale of assets under fifty million |  |  | 3.00% |  |
Asset sale commission threshold |  |  | $ 50,000,000 |  |
Percentage commissions on sale of assets over fifty million |  |  | 1.00% |  |
Other liabilities | 492,000 |  | $ 492,000 |  | $ 100,000
Related Party | Property management, cleaning, engineering, parking and security fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Other liabilities | $ 473,000 |  | $ 473,000 |  |
Related Party | Retail Space | Rego Park Shopping Center | Property management fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Property management fee, percent fee |  |  | 2.00% |  |
Related Party | Office and Retail Space | 731 Lexington Avenue | Property management fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Property management fee agreement, price per square foot | $ / ft² |  |  | 0.50 |  |
Related Party | Common Area | 731 Lexington Avenue | Property management fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Property management fee escalation percentage per annum |  |  | 3.00% |  |
Related Party | Common Area | 731 Lexington Avenue | Management and development agreement, base management fee |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Fees to related party |  |  | $ 399,000 |  |
Vornado | Leasing fees |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Asset sale commission threshold |  |  | $ 50,000,000 |  |
Alexander's Inc. | Related Party | Vornado |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Subsidiary, ownership percentage, parent | 32.40% |  | 32.40% |  |

X
- Definition Asset sale commission threshold. + References No definition available. + Details
Name: | alx_AssetSaleCommissionThreshold
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of development costs that the related party will receive as per the Development agreement. + References No definition available. + Details
Name: | alx_DevelopmentFeePercentage
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lease Commission, Percentage + References No definition available. + Details
Name: | alx_LeaseCommissionPercentage
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of rent payable to related party for leasing services for the eleventh through twentieth years of the lease. + References No definition available. + Details
Name: | alx_LeaseFeePercentageOfRentElevenToTwentyYears
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of rent payable to related party for leasing services for the first ten years of the lease. + References No definition available. + Details
Name: | alx_LeaseFeePercentageOfRentOneToTenYears
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of rent payable to related party for leasing services for the twenty-first through thirtieth years of the lease. + References No definition available. + Details
Name: | alx_LeaseFeePercentageOfRentTwentyFirstToThirtyYears
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of management fee paid to related party to manage corporate activities. + References No definition available. + Details
Name: | alx_ManagementFeeAgreementValue
Namespace Prefix: | alx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of gross proceeds over $50,000,000 from the sale of any assets, payable to related party. + References No definition available. + Details
Name: | alx_PercentageCommissionsOnSaleOfAssetsOverFiftyMillion
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of gross proceeds under $50,000,000 from the sale of any assets, payable to related party. + References No definition available. + Details
Name: | alx_PercentageCommissionsOnSaleOfAssetsUnderFiftyMillion
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Property Management Fee Agreement, Price Per Square Foot + References No definition available. + Details
Name: | alx_PropertyManagementFeeAgreementPricePerSquareFoot
Namespace Prefix: | alx_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Annual increase in the amount paid to related party as property management fees. + References No definition available. + Details
Name: | alx_PropertyManagementFeeEscalationPercentagePerAnnum
Namespace Prefix: | alx_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of liabilities classified as other. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(24)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480657/210-10-S50-8 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(23)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)(5)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 10: http://www.xbrl.org/2003/role/exampleRef -Topic 480 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 64 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481620/480-10-55-64 Reference 11: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 605 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477548/944-605-55-14 Reference 12: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 605 -Name Accounting Standards Codification -Section 55 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477548/944-605-55-11 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(15)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 14: http://www.xbrl.org/2003/role/exampleRef -Topic 946 -SubTopic 830 -Name Accounting Standards Codification -Section 55 -Paragraph 12 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479168/946-830-55-12 Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(12)(b)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(12)(b)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1 Reference 17: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(12)(b)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1 Reference 18: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(17)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_OtherLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of cash paid for commissions during the current period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 25 -Subparagraph (g) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-25 + Details
Name: | us-gaap_PaymentsForCommissions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The percentage charged for managing real estate properties. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-2 + Details
Name: | us-gaap_PropertyManagementFeePercentFee
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of transactions with related party during the financial reporting period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 850 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483326/850-10-50-1 + Details
Name: | us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(e)(1)(i)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(2)(g)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 970 -SubTopic 810 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477383/970-810-45-1 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 850 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483326/850-10-50-1 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 850 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483326/850-10-50-1 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 850 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483326/850-10-50-3 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(k)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(k)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 13 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481990/310-10-45-13 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(2)(c)(2)(i)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07(2)(c)(2)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1 + Details
Name: | us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=alx_DevelopmentFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=alx_LeasingFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=alx_PropertyManagementCleaningEngineeringParkingAndSecurityFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_RelatedPartyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | alx_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxisAxis=alx_RegoParkIPropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=alx_RegoParkShoppingCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=alx_PropertyManagementFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=alx_LexingtonAvenuePropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=alx_ManagementAndDevelopmentAgreementBaseManagementFeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=alx_AlexandersInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=alx_VornadoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |