Number of real estate ventures.

No definition available.

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- Definition

Amount of real estate venture promote interest to be paid to certain individuals.

+ References

No definition available.

+ Details

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- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

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Balance Type:	na
Period Type:	duration

- 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

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

The carrying amount of investments in unconsolidated real estate and other joint ventures not separately presented. This includes direct and indirect investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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Balance Type:	debit
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- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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Subsequent Events (Details) $ / shares in Units, $ in Thousands		1 Months Ended
	Apr. 29, 2021 $ / shares	Apr. 30, 2021 USD ($) ft² item	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Subsequent Event [Line Items]
Investments in unconsolidated real estate ventures \| $			$ 455,476	$ 461,369
Subsequent Event
Subsequent Event [Line Items]
Dividends cash declared \| $ / shares	$ 0.225
Subsequent Event \| Unconsolidated Real Estate Ventures \| Potomac Yard Mixed Use Development
Subsequent Event [Line Items]
Number of real estate ventures \| item		2
Ownership interest (as percent)		50.00%
Area of real estate property \| ft²		2,000,000.0
Real estate venture promote interest expected to be paid \| $		$ 17,500
Subsequent Event \| Unconsolidated Real Estate Ventures \| Potomac Yard Mixed Use Development \| Non-employee Trustees and Certain Executives
Subsequent Event [Line Items]
Real estate venture promote interest expected to be paid \| $		$ 4,300
Subsequent Event \| Unconsolidated Real Estate Ventures \| Potomac Yard Landbay G
Subsequent Event [Line Items]
Area of real estate property \| ft²		700,000
Subsequent Event \| Venture Partner \| Unconsolidated Real Estate Ventures \| Potomac Yard Landbay F
Subsequent Event [Line Items]
Area of real estate property \| ft²		1,300,000