Organization and Basis of Presentation - Narrative (Details) $ in Billions	Mar. 31, 2021 USD ($) ft² property building
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	63
Under-construction assets
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	2
Near-term Development
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	9
Area of real estate property \| ft²	4,800,000
Future Development
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	29
Area of real estate property \| ft²	14,800,000
Commercial Real Estate
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	42
Area of real estate property \| ft²	13,300,000
Multifamily
Real Estate Properties [Line Items]
Number of Real Estate Properties \| property	21
Number of Units in Real Estate Property \| building	7,800
Multifamily \| Under-construction assets
Real Estate Properties [Line Items]
Number of Units in Real Estate Property \| building	1,130
Wholly Owned Properties \| Future Development
Real Estate Properties [Line Items]
Area of real estate property \| ft²	12,000,000.0
Wholly Owned Properties \| Commercial Real Estate
Real Estate Properties [Line Items]
Area of real estate property \| ft²	11,400,000
Wholly Owned Properties \| Multifamily
Real Estate Properties [Line Items]
Number of Units in Real Estate Property \| building	5,999
Wholly Owned Properties \| Multifamily \| Under-construction assets
Real Estate Properties [Line Items]
Number of Units in Real Estate Property \| ft²	969
Virginia Tech's
Real Estate Properties [Line Items]
Investments \| $	$ 1
JBG Smith, LP
Real Estate Properties [Line Items]
Ownership interest by parent	90.50%

Area of a real estate property.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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

+ References

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The number of units in a real estate property owned as of the balance sheet date.

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Amount of real estate investments, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; (7) other real estate investments; (8) real estate joint ventures; and (9) unconsolidated real estate and other joint ventures not separately presented.

+ 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

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