Real Estate Properties - Schedule of Unconsolidated Joint Ventures (Details) - Unconsolidated Joint Ventures $ in Thousands	Dec. 31, 2019 USD ($) ft² property	Dec. 31, 2018 USD ($)
Real Estate [Line Items]
OPI Carrying Value of Investment at December 31, | $	$ 39,756	$ 43,665
Number of properties | property	3
Square feet (in square feet) | ft²	443,867
Prosperity Metro Plaza
Real Estate [Line Items]
OPI Ownership	51.00%
OPI Carrying Value of Investment at December 31, | $	$ 22,483	23,969
Number of properties | property	2
Square feet (in square feet) | ft²	328,456
1750 H Street, NW
Real Estate [Line Items]
OPI Ownership	50.00%
OPI Carrying Value of Investment at December 31, | $	$ 17,273	$ 19,696
Number of properties | property	1
Square feet (in square feet) | ft²	115,411