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Transactions with Vornado and Related Parties (Details) |  |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 18, 2017 USD ($) | Jul. 17, 2017 USD ($) | Jun. 30, 2016 USD ($) ft² | Aug. 31, 2014 USD ($) ft² | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Borrowings under revolving credit facility |  |  |  |  | $ 200,000,000 | $ 35,000,000 | $ 115,751,000
Qualified Affordable Housing Project Investments, Total Capital Commitments |  |  |  |  | 104,800,000 |  |
Corporate and other |  |  |  |  | 46,822,000 | 33,728,000 | 39,350,000
Affiliated Entity [Member] | Washington Housing Initiative [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Qualified Affordable Housing Project Investments, Commitment |  |  |  |  | 10,200,000 |  |
Affiliated Entity [Member] | Legacy JBG Funds [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Corporate and other |  |  |  |  | 5,000,000.0 | 4,900,000 | 2,200,000
Affiliated Entity [Member] | Separation and Combination transaction | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Expenses from related parties |  |  |  |  | 3,600,000 | 2,200,000 |
Revenue from related parties |  |  |  |  | 2,000,000.0 | 2,100,000 | 779,000
Affiliated Entity [Member] | Supervisory Services of Properties [Member] | BMS |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Related party transaction amount |  |  |  |  | 21,800,000 | 20,900,000 | 13,600,000
Affiliated Entity [Member] | Allocations of Centralized Corporate Costs [Member] | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party |  |  |  |  |  |  | 13,000,000.0
Affiliated Entity [Member] | Fees from Legacy JBG Funds and Washington Housing Initiative [Member] | Legacy JBG Funds and Washington Housing Initiative [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Third-party real estate services, including reimbursements |  |  |  |  | 36,500,000 |  |
Accounts Receivable, Related Parties |  |  |  |  | $ 6,200,000 |  |
Affiliated Entity [Member] | Fees from Legacy JBG Funds | Legacy JBG Funds [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Third-party real estate services, including reimbursements |  |  |  |  |  | 33,800,000 | 19,900,000
Accounts Receivable, Related Parties |  |  |  |  |  | $ 3,600,000 |
Director [Member] | Consulting Agreement [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Expenses from related parties |  |  |  |  |  |  | 16,400,000
Related Party Transaction, Monthly Transaction Amount |  | $ 169,400 |  |  |  |  |
Related Party Transaction, Initial Potential Service Period |  | 24 years |  |  |  |  |
Note Agreement for Development of The Bartlett [Member] | Affiliated Entity [Member] | Financing Transactions [Member] | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount | $ 170,000,000.0 |  |  |  |  |  |
Interest Expense, Related Party |  |  |  |  |  |  | 4,100,000
Financing of the Universal Buildings [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  | $ 185,000,000.0 |  |  |
Financing of the Universal Buildings [Member] | Affiliated Entity [Member] | Financing Transactions [Member] | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Origination of Notes Receivable from Related Parties |  |  |  | $ 86,000,000.0 |  |  |
Interest Income, Related Party |  |  |  |  |  |  | 1,800,000
Mortgage loan secured by Bowen Building [Member] | Affiliated Entity [Member] | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Interest Expense, Related Party |  |  |  |  |  |  | $ 1,300,000
Repayments of Secured Debt |  |  | $ 115,000,000.0 |  |  |  |
Debt Instrument, Increase, Accrued Interest |  |  | 608,000 |  |  |  |
Borrowings under revolving credit facility |  |  | $ 115,600,000 |  |  |  |
Universal Buildings, Washington DC [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Area of real estate property (in square feet) | ft² |  |  | 231,000 | 687,000 |  |  |
London Interbank Offered Rate (LIBOR) [Member] | Financing of the Universal Buildings [Member] | Affiliated Entity [Member] | Financing Transactions [Member] | Vornado Realty Trust [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  |  | 2.90% |  |  |
JBG Companies [Member] |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Liabilities Incurred | $ 4,100,000 |  |  |  |  |  |

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