Aggregate Principal Amounts due on Mortgage and Construction Notes Payable by Unconsolidated LLC's/LPs Accounted Under Equity Method (Detail) - Equity Method Investments - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Mortgage Loan Balance	[1]	$ 36,525	$ 26,650
FTX MOB Phase II
Schedule Of Equity Method Investments [Line Items]
Mortgage Loan Balance	[1],[2]	$ 4,814	4,926
Maturity Date	[2]	2021-02
Grayson Properties
Schedule Of Equity Method Investments [Line Items]
Mortgage Loan Balance	[1],[3]	$ 13,442	13,658
Maturity Date	[3]	2021-09
Brunswick Associates
Schedule Of Equity Method Investments [Line Items]
Mortgage Loan Balance	[1]	$ 7,917	$ 8,066
Maturity Date		2024-12
Grayson Properties II LP
Schedule Of Equity Method Investments [Line Items]
Mortgage Loan Balance	[1],[4]	$ 10,352
Maturity Date	[4]	2025-06

[1] All mortgage loans require monthly principal payments through maturity and include a balloon principal payment upon maturity

[2] This loan, originally scheduled to mature on October 1, 2020, was extended with a new maturity date of February 1, 2021, at which time the venture intends to refinance pursuant to a new mortgage loan.

[3] This loan is scheduled to mature within the next twelve months, at which time the venture intends to refinance pursuant to a new mortgage loan.

[4] This construction loan has a maximum balance of $13.1 million and requires unpaid interest on the outstanding principal balance to be paid on a monthly basis through December 1, 2022.  Principal and accrued interest monthly payments will commence on January 1, 2023.