Commitments and Contingencies - Additional Information (Detail) ft² in Thousands	1 Months Ended			9 Months Ended
	Mar. 31, 2016 USD ($)	Jun. 30, 2014 USD ($) ft²	Feb. 28, 2014 fire	Sep. 30, 2021 USD ($)
Loss Contingencies [Line Items]
Standby letters of credit, outstanding				$ 960,000
Rego Park I | Sears
Loss Contingencies [Line Items]
Area of property (in sqft.) | ft²		195
Number of fires | fire			2
Rego Park I | Sears | Estimated Future Damages
Loss Contingencies [Line Items]
Loss contingency, damages sought, value	$ 650,000
Rego Park I | Sears | Minimum
Loss Contingencies [Line Items]
Loss contingency, damages sought, value		$ 4,000,000
Rego Park I | Sears | Minimum | Estimated Future Damages
Loss Contingencies [Line Items]
Loss contingency, damages sought, value		$ 25,000,000
Rego Park I | Sears | Maximum | Estimated Future Damages
Loss Contingencies [Line Items]
Reasonably possible losses				650,000
All Risk Property and Rental Value
Loss Contingencies [Line Items]
Insurance maximum coverage per occurrence				1,700,000,000
Terrorism Coverage Including NBCR
Loss Contingencies [Line Items]
Insurance maximum coverage per occurrence				1,700,000,000
Insurance maximum coverage in aggregate				$ 1,700,000,000
NBCR
Loss Contingencies [Line Items]
Federal government responsibility				80.00%
NBCR | FNSIC
Loss Contingencies [Line Items]
Insurance deductible				$ 275,000
Self insured responsibility				20.00%
General Liability
Loss Contingencies [Line Items]
Insurance maximum coverage per occurrence				$ 300,000,000
Insurance maximum coverage per property				300,000,000
Disease Coverage
Loss Contingencies [Line Items]
Insurance maximum coverage per occurrence				$ 30,000,000