Limited Partners Capital Account, Units Split, Conversion Ratio

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Percentage Of Outstanding Common Shares Distributed

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Area of a real estate property.

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Number of shares of equity interests issued or issuable to acquire entity.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Other operating costs incurred during the reporting period and may include amounts paid to maintain the property.

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The number of limited partner units issued.

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The number of limited partner units outstanding.

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Amount of expenses related to the managing member or general partner for management of the day-to-day business functions of the limited liability company (LLC) or limited partnership (LP).

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Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

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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.

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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 assets classified as other.

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Amount of revenue and income classified as other.

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

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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.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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Organization and Basis of Presentation - Narrative (Details) shares in Thousands, $ in Thousands				12 Months Ended
	Jul. 18, 2017 ft² building_unit properties shares	Jul. 17, 2017 shares	Jul. 07, 2017	Dec. 31, 2017 USD ($) ft² building_unit property properties shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Common stock issued (in shares) \| shares		94,700		117,955
Common limited partnership units (in shares) \| shares		5,800
Outstanding common shares and common limited partnership units (in shares) \| shares	118,000			117,955
Common limited partnership units outstanding (in shares) \| shares	19,800
Number of real estate properties \| properties				69
Other assets, net \| $				$ 263,923	$ 112,955
Investments in and advances to unconsolidated real estate ventures \| $				261,811	45,776
Third-party real estate services \| $				51,919	19,066	$ 18,217
Property operating \| $				111,055	100,304	101,511
Third-party real estate services, including reimbursements \| $				63,236	33,882	29,467
Other income \| $				$ 5,167	5,381	10,854
Asset under Construction
Real Estate Properties [Line Items]
Number of real estate properties \| properties				10
Future Development
Real Estate Properties [Line Items]
Number of real estate properties \| properties				43
Area of real estate property (in square feet)				21,400,000
Office Building
Real Estate Properties [Line Items]
Number of real estate properties \| properties				51
Area of real estate property (in square feet)				13,700,000
Office Building \| Asset under Construction
Real Estate Properties [Line Items]
Number of real estate properties \| properties				4
Area of real estate property (in square feet)				1,300,000
Multifamily
Real Estate Properties [Line Items]
Number of real estate properties \| properties				14
Number of building units \| building_unit				6,016
Multifamily \| Asset under Construction
Real Estate Properties [Line Items]
Number of real estate properties \| properties				5
Number of building units \| building_unit				1,767
Other Property
Real Estate Properties [Line Items]
Number of real estate properties \| properties				4
Area of real estate property (in square feet)				765,000
Other Property \| Asset under Construction
Real Estate Properties [Line Items]
Number of real estate properties \| property				1
Area of real estate property (in square feet)				41,100
Wholly Owned Properties \| Future Development
Real Estate Properties [Line Items]
Area of real estate property (in square feet)				17,900,000
Wholly Owned Properties \| Office Building
Real Estate Properties [Line Items]
Area of real estate property (in square feet)				11,800,000
Wholly Owned Properties \| Office Building \| Asset under Construction
Real Estate Properties [Line Items]
Area of real estate property (in square feet)				1,200,000
Wholly Owned Properties \| Multifamily
Real Estate Properties [Line Items]
Number of building units \| building_unit				4,232
Wholly Owned Properties \| Multifamily \| Asset under Construction
Real Estate Properties [Line Items]
Number of building units \| building_unit				1,568
Wholly Owned Properties \| Other Property
Real Estate Properties [Line Items]
Area of real estate property (in square feet)				348,000
Wholly Owned Properties \| Other Property \| Asset under Construction
Real Estate Properties [Line Items]
Area of real estate property (in square feet)				4,100
JBG Smith, LP
Real Estate Properties [Line Items]
Ownership interest by parent	85.60%
JBG Companies
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration (in shares) \| shares	37,164
Outstanding common shares and common limited partnership units (in shares) \| shares		100,571
Number of real estate properties \| properties	30
JBG Companies \| Asset under Construction
Real Estate Properties [Line Items]
Number of real estate properties \| properties	11
Area of real estate property (in square feet)	2,500,000
JBG Companies \| Future Development
Real Estate Properties [Line Items]
Number of real estate properties \| properties	26
Area of real estate property (in square feet)	11,700,000
JBG Companies \| Office Building
Real Estate Properties [Line Items]
Number of real estate properties \| properties	19
Area of real estate property (in square feet)	3,600,000
JBG Companies \| Multifamily
Real Estate Properties [Line Items]
Number of real estate properties \| properties	9
Number of building units \| building_unit	2,883
JBG Companies \| Other Property
Real Estate Properties [Line Items]
Number of real estate properties \| properties	2
Area of real estate property (in square feet)	490,000
JBG Companies \| Wholly Owned Properties \| Asset under Construction
Real Estate Properties [Line Items]
Area of real estate property (in square feet)	2,200,000
JBG Companies \| Wholly Owned Properties \| Future Development
Real Estate Properties [Line Items]
Area of real estate property (in square feet)	8,500,000
JBG Companies \| Wholly Owned Properties \| Office Building
Real Estate Properties [Line Items]
Area of real estate property (in square feet)	2,300,000
JBG Companies \| Wholly Owned Properties \| Multifamily
Real Estate Properties [Line Items]
Number of building units \| building_unit	1,099
JBG Companies \| Wholly Owned Properties \| Other Property
Real Estate Properties [Line Items]
Area of real estate property (in square feet)	73,000
JBG Companies \| Common Shares
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration (in shares) \| shares	23,200
JBG Companies \| Partnership units
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration (in shares) \| shares	13,900
Affiliate \| Vornado
Real Estate Properties [Line Items]
Percentage of common shares distributed		100.00%
Spinoff ratio			0.5
Limited Partners spinoff ratio			0.5
Reclassification Adjustment
Real Estate Properties [Line Items]
Other assets, net \| $					4,000
Investments in and advances to unconsolidated real estate ventures \| $					(4,000)
Third-party real estate services \| $					19,100	18,200
Property operating \| $					(19,100)	(18,200)
Third-party real estate services, including reimbursements \| $					16,400	15,900
Other income \| $					$ (16,400)	$ (15,900)
Five Assets \| Annualized Rent \| Asset Concentration Risk
Real Estate Properties [Line Items]
Concentration risk percentage					25.00%