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Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Additional Information (Detail) - USD ($) |  |  |  |  |  |  |  | 12 Months Ended |  |  |  |
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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% |  |  |  |  |  |  |  |  |  |

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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)(a)(2)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585 + Details
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