Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 13.2	$ 7.7	$ 23.3
Restricted cash and cash equivalents	457.7	410.0	410.9
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 470.9	$ 417.7	$ 434.2	$ 396.2