Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 25.7	$ 187.4	$ 41.3	$ 25.7
Restricted cash and cash equivalents	408.1	330.3	417.9	303.6
Total cash, cash equivalents, restricted cash and restricted cash equivalents	$ 433.8	$ 517.7	$ 459.2	$ 329.3