Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Additional Information (Detail) - USD ($)								12 Months Ended
	Dec. 31, 2021	Nov. 19, 2021	Aug. 31, 2021	Jun. 11, 2021	Jan. 05, 2021	Jul. 24, 2020	Jul. 14, 2020	Dec. 31, 2021	Dec. 31, 2020	Mar. 03, 2020	Feb. 10, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Outstanding debt	$ 1,200,000,000							$ 1,200,000,000
Fixed rate mortgages	941,456,000							941,456,000	$ 827,603,000
Variable rate debt	99,233,000							99,233,000	74,791,000
Long-term debt repayments of principal and balloon payments	1,155,028,000							1,155,028,000	1,200,000,000
Debt outstanding with fixed-rate									980,800,000
Debt outstanding with variable-rate									179,500,000
Revolving credit facility payable	103,167,000							103,167,000	103,913,000
Remaining loan balance	237,410,000							237,410,000
Unamortized deferred debt costs	11,172,000							11,172,000	9,300,000
Accumulated amortization	7,700,000							7,700,000	8,700,000
Capitalization of debt issuance cost	$ 6,400,000							6,400,000	1,200,000			$ 1,000,000
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR	1.35%
Revolving Credit Facility | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR			1.35%
Revolving Credit Facility | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR			1.95%
Term Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR	1.30%
Term Facility | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR			1.30%
Term Facility | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread on LIBOR			1.90%
Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Available borrowing capacity	$ 219,800,000							219,800,000
Revolving credit facility payable	106,000,000							106,000,000
Letter of Credit
Debt Instrument [Line Items]
Revolving credit facility payable	185,000							185,000
Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 525,000,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			425,000,000
Line of Credit | Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 100,000,000
Mortgages | Jamestown Place
Debt Instrument [Line Items]
Payment for debt extinguishment or debt prepayment cost					$ 6,100,000
Mortgages | Hunt Club Corners
Debt Instrument [Line Items]
Payment for debt extinguishment or debt prepayment cost				$ 5,000,000
Mortgage Notes Payable
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure	41,000,000							41,000,000	41,000,000
Fixed rate mortgage notes payable
Debt Instrument [Line Items]
Fixed rate mortgages	949,000,000							949,000,000	980,800,000
Variable rate loans payable
Debt Instrument [Line Items]
Variable rate debt	206,000,000							206,000,000
Broadlands Village
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure	3,700,000							3,700,000
Remaining loan balance	29,600,000							29,600,000
Avenel Business Park
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure	6,300,000							6,300,000
Remaining loan balance	24,100,000							24,100,000
Waycroft Construction Loan
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure	23,600,000							23,600,000
Remaining loan balance	156,100,000							156,100,000
Ashbrook Marketplace
Debt Instrument [Line Items]
Remaining loan balance	21,300,000							21,300,000
Ashbrook Marketplace | 3.80% Fixed Rate Loan Maturing In 2035
Debt Instrument [Line Items]
Loan term							15 years
Loan amount							$ 22,100,000
Loan fixed interest rate							3.80%
Loan required periodic principal and interest payment							$ 114,226
Amortization schedule							25 years
Balloon payment to be paid							$ 11,500,000
Ashbrook Marketplace | 3.43% Fixed Rate Loan Maturing in 2035
Debt Instrument [Line Items]
Loan term						15 years
Loan amount						$ 30,000,000
Loan fixed interest rate						3.43%
Loan required periodic principal and interest payment						$ 149,064
Amortization schedule						25 years
Balloon payment to be paid						$ 15,300,000
Kentlands Square I
Debt Instrument [Line Items]
Remaining loan balance	28,900,000							28,900,000
Boca Valley Plaza
Debt Instrument [Line Items]
Remaining loan balance											$ 9,200,000
Palm Springs Center
Debt Instrument [Line Items]
Remaining loan balance										$ 7,100,000
Debt Covenant
Debt Instrument [Line Items]
Carrying value of properties collateralized	1,100,000,000							$ 1,100,000,000	$ 1,200,000,000
Credit agreement leverage ratio								60.00%
Interest coverage ratio required minimum								2.0
Required fixed charge coverage ratio								1.4
New Facility | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	$ 106,000,000							$ 106,000,000
Twinbrook Quarter | 3.80% Fixed Rate Loan Maturing In 2035
Debt Instrument [Line Items]
Loan amount		$ 145,000,000
Amortization schedule		25 years
Twinbrook Quarter | 3.83% Fixed Rate Loan Maturing In 2041
Debt Instrument [Line Items]
Loan fixed interest rate		3.83%