INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - JGB Ventures (Details)	Dec. 31, 2020 property	May 29, 2015 a
Schedule of Equity Method Investments [Line Items]
Number of properties \| property	82
JBG 51 N 50 Patterson
Schedule of Equity Method Investments [Line Items]
Ownership percentage	70.00%	70.00%
Area owned by real estate venture of undeveloped parcels of land \| a		0.9
JBG 1250 First Street Office
Schedule of Equity Method Investments [Line Items]
Ownership percentage	70.00%	70.00%
Area owned by real estate venture of undeveloped parcels of land \| a		0.5
JBG Ventures
Schedule of Equity Method Investments [Line Items]
Number of properties \| property	2
JBG Ventures \| JBG 51 N 50 Patterson
Schedule of Equity Method Investments [Line Items]
Ownership percentage		30.00%
JBG Ventures \| JBG 1250 First Street Office
Schedule of Equity Method Investments [Line Items]
Ownership percentage		30.00%

Area owned by Real estate venture of undeveloped parcels of land (in acres).

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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