Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 8.9	$ 187.4	$ 24.7	$ 25.7
Restricted cash and cash equivalents	391.9	330.3	329.8	303.6
Total cash, cash equivalents, restricted cash and restricted cash equivalents	$ 400.8	$ 517.7	$ 354.5	$ 329.3