Related Party Transactions - Additional Information (Detail) | 3 Months Ended | 6 Months Ended | |
Jun. 30, 2023 USD ($) | Jun. 30, 2022 USD ($) | Jun. 30, 2023 USD ($) $ / ft² | Jun. 30, 2022 USD ($) | Dec. 31, 2022 USD ($) |
Related Party Transaction [Line Items] | | | | | |
Related party transaction, amounts of transaction | $ 3,090,000 | $ 2,247,000 | $ 5,240,000 | $ 5,537,000 | |
Amounts due to Vornado | 952,000 | | 952,000 | | $ 801,000 |
Management And Development Agreement, Base Management Fee | 731 Lexington Avenue | Common Area | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related party transaction, amounts of transaction | | | $ 365,000 | | |
Leasing and Other Agreements, Percentage of Gross Proceeds Used for Commission for Sales Less Than Fifty Million | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related party transaction, rate | | | 3% | | |
Asset sale commission threshold | | | $ 50,000,000 | | |
Leasing and Other Agreements, Percentage of Gross Proceeds Used For Commission for Sales Greater Than Fifty Million | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related party transaction, rate | | | 1% | | |
Asset sale commission threshold | | | $ 50,000,000 | | |
Leasing fees | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related party transaction, amounts of transaction | 129,000 | $ 0 | 170,000 | $ 1,318,000 | |
Related Party | Rego Park III Land Parcel | | | | | |
Related Party Transaction [Line Items] | | | | | |
Payments for commissions | 711,000 | | | | |
Related Party | Management and Development Agreement | | | | | |
Related Party Transaction [Line Items] | | | | | |
Annual management fee | | | $ 2,800,000 | | |
Related Party | Management and Development Agreement | 731 Lexington Avenue | Office and Retail Space | | | | | |
Related Party Transaction [Line Items] | | | | | |
Property management fee agreement, price per square foot | $ / ft² | | | 0.50 | | |
Related Party | Management and Development Agreement, Percentage of Gross Revenue | Rego Park II | Retail Space | | | | | |
Related Party Transaction [Line Items] | | | | | |
Property management fee agreement percentage of annual escalation | | | 2% | | |
Related Party | Management and Development Agreement, Annualized Management Fee | 731 Lexington Avenue | Common Area | | | | | |
Related Party Transaction [Line Items] | | | | | |
Property management fee agreement percentage of annual escalation | | | 3% | | |
Related Party | Management and Development Agreement, Development Fee | | | | | |
Related Party Transaction [Line Items] | | | | | |
Property management fee agreement percentage of annual escalation | | | 6% | | |
Related Party | Leasing and Other Agreements, Percentage of Rent for First Ten Years | | | | | |
Related Party Transaction [Line Items] | | | | | |
Service fees, rate | | | 3% | | |
Related Party | Leasing and Other Agreements, Percentage of Rent for Eleventh Through Twentieth Year | | | | | |
Related Party Transaction [Line Items] | | | | | |
Service fees, rate | | | 2% | | |
Related Party | Leasing and Other Agreements, Percentage of Rent for the Twenty-First Through the Thirtieth Year | | | | | |
Related Party Transaction [Line Items] | | | | | |
Service fees, rate | | | 1% | | |
Related Party | Leasing and Other Agreements, Percentage Increase in Fee if Third Party is Used | | | | | |
Related Party Transaction [Line Items] | | | | | |
Service fees, rate | | | 1% | | |
Related Party | Management, property management, cleaning, engineering and security fees | | | | | |
Related Party Transaction [Line Items] | | | | | |
Amounts due to Vornado | 823,000 | | $ 823,000 | | 742,000 |
Related Party | Leasing fees | | | | | |
Related Party Transaction [Line Items] | | | | | |
Amounts due to Vornado | $ 129,000 | | $ 129,000 | | $ 59,000 |
Vornado | Alexander's Inc. | Related Party | | | | | |
Related Party Transaction [Line Items] | | | | | |
Ownership percentage by noncontrolling owners | 32.40% | | 32.40% | | |