Dispositions and Assets Held for Sale (Details) $ in Thousands	Jun. 30, 2021 USD ($) ft²	Dec. 31, 2020 USD ($) ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale	$ 73,876	$ 73,876
Disposal Group, Held-for-sale | Pen Place | Arlington, Virginia
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property | ft²	2,082	2,082
Assets held for sale	$ 73,876	$ 73,876