Investments in Real Estate (Acquisitions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Purchase price	$ 75.7	$ 410.7
Land parcels
Business Acquisition [Line Items]
Purchase price	47.7	296.1
Data Centers
Business Acquisition [Line Items]
Purchase price		$ 114.6
Technology Office [Member]
Business Acquisition [Line Items]
Purchase price	$ 28.0