Leases - Lessor (Details) ft² in Thousands, $ in Thousands			6 Months Ended	12 Months Ended
	May 03, 2024 USD ($) ft²	Dec. 03, 2022 USD ($) ft²	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2024 USD ($)
Lessor, Lease, Description [Line Items]
Revenues				$ 226,374	$ 224,962	$ 205,814
Lease incentive liabilities				115,118	0
Revenue Benchmark | Bloomberg | Customer Concentration Risk
Lessor, Lease, Description [Line Items]
Revenues				$ 125,349	$ 120,351	$ 115,129
Percentage rent contributed by tenant				55.00%	54.00%	56.00%
Minimum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)				5 years
Maximum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)				25 years
The Alexander apartment tower
Lessor, Lease, Description [Line Items]
Area of property (in square feet) | ft²				255
The Alexander apartment tower | Minimum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)				1 year
The Alexander apartment tower | Maximum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)				2 years
Rego Park I
Lessor, Lease, Description [Line Items]
Area of property (in square feet) | ft²				338
Rego Park I | IKEA
Lessor, Lease, Description [Line Items]
Area of property (in square feet) | ft²		112
Payment for termination of lease		$ 10,000	$ 10,000
731 Lexington Avenue Property | Bloomberg L.P.
Lessor, Lease, Description [Line Items]
Area of property (in square feet) | ft²	947
Renewal term	11 years
Payments for lease commissions	$ 32,000
Lease incentive liabilities	113,618						$ 113,618
Incentive asset from lessor							$ 113,618
731 Lexington Avenue Property | Bloomberg L.P. | Third Party Broker
Lessor, Lease, Description [Line Items]
Payments for lease commissions	26,500
731 Lexington Avenue Property | Bloomberg L.P. | Vornado
Lessor, Lease, Description [Line Items]
Payments for lease commissions	$ 5,500