Real Estate Transactions - Narrative (Details) - Discontinued Operations, Disposed of by Sale $ in Millions	1 Months Ended
	Mar. 31, 2020 USD ($) ft²	Feb. 28, 2019 USD ($) a	May 31, 2020 USD ($) ft²	Feb. 29, 2020 USD ($) ft²
Hearst Tower
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of property | ft²	966,000		1,550
Gross sales price of property sold	$ 455.5		$ 85.0
Gain from sale of property	$ 90.4
Woodcrest
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of property | ft²				386,000
Gross sales price of property sold				$ 25.3
Downtown Atlanta, Georgia
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of property | a		8
Gross sales price of property sold		$ 13.3
Gain from sale of property		$ 13.1