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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Description of reference rate used for variable rate of debt instrument.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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The aggregate amount of the participation liability at the end of the accounting period.

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Mortgages Payable - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Apr. 07, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages payable, net of deferred debt issuance costs	$ 1,157,263		$ 1,156,170
Mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages payable, net of deferred debt issuance costs	$ 1,157,263		1,156,170
731 Lexington Avenue \| Office Space \| Mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Debt instrument, description of variable rate basis	LIBOR
Interest rate (in percentage)	0.98%
731 Lexington Avenue \| Office Space \| Mortgages \| LIBOR
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Basis spread over LIBOR	0.90%
731 Lexington Avenue \| Retail Space \| Mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest rate (in percentage)	1.72%
731 Lexington Avenue \| Retail Space \| Mortgages \| Interest Rate Swap
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest rate (in percentage)	1.72%
731 Lexington Avenue \| Retail Space \| Mortgages \| LIBOR
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Debt instrument, description of variable rate basis	LIBOR
Basis spread over LIBOR	1.40%
Rego Park II \| Retail Space \| Mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Debt instrument, description of variable rate basis	LIBOR
Interest rate (in percentage)	1.43%
Rego Park II \| Retail Space \| Mortgages \| LIBOR
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Basis spread over LIBOR	1.35%
Participation Agreement \| Rego Park II \| Retail Space \| Mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages payable, net of deferred debt issuance costs		$ 202,544	252,544
Loan participation balance			$ 50,000