Real Estate Properties - Schedule of Joint Ventures (Details) $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($) ft² property joint_venture	Dec. 31, 2018 USD ($)
Real Estate [Line Items]
Number of joint ventures \| joint_venture	2
Unconsolidated Joint Ventures
Real Estate [Line Items]
Number of Properties \| property	3
Investment at carrying value	$ 40,502	$ 43,665
Square Feet (in square feet) \| ft²	443,867
Unamortized basis difference	$ 8,074
Unconsolidated Joint Ventures \| Prosperity Metro Plaza
Real Estate [Line Items]
Number of Properties \| property	2
Ownership percentage	51.00%
Investment at carrying value	$ 22,857	23,969
Square Feet (in square feet) \| ft²	328,456
Unconsolidated Joint Ventures \| 1750 H Street, NW
Real Estate [Line Items]
Number of Properties \| property	1
Ownership percentage	50.00%
Investment at carrying value	$ 17,645	$ 19,696
Square Feet (in square feet) \| ft²	115,411
Mortgages \| Unconsolidated Joint Ventures
Real Estate [Line Items]
Interest rate (as a percent)	3.93%
Debt Instrument, Face Amount	$ 82,000
Mortgages \| Unconsolidated Joint Ventures \| Prosperity Metro Plaza
Real Estate [Line Items]
Interest rate (as a percent)	4.09%
Debt Instrument, Face Amount	$ 50,000
Mortgages \| Unconsolidated Joint Ventures \| 1750 H Street, NW
Real Estate [Line Items]
Interest rate (as a percent)	3.69%
Debt Instrument, Face Amount	$ 32,000

Number Of Joint Ventures

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- Definition

Area of a real estate property.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee.

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

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

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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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