Investments in Real Estate (Acquisitions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Purchase price	$ 410.7	$ 415.8
Land parcels
Business Acquisition [Line Items]
Purchase price	296.1	55.3
Data Centers
Business Acquisition [Line Items]
Purchase price	$ 114.6	346.2
Technology Manufacturing
Business Acquisition [Line Items]
Purchase price		$ 14.3