Basis of Presentation - Additional Information (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Decrease to mortgages payable, net of deferred debt issuance costs		$ (968,386)		$ (965,826)
Number of reportable segments | segment		1
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Rego Park II Loan Participation				195,708
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Property rentals	$ 38,618		$ 76,859
Expense reimbursements	$ 19,635		$ 39,274
Restatement to reclassify Rego Park II as a reduction to mortgage payable, net of deferred debt issuance costs | Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Decrease to mortgages payable, net of deferred debt issuance costs				$ 195,708