Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) reporting_unit	Dec. 31, 2020 USD ($)	Jan. 01, 2019 USD ($)
Accounting Policies [Abstract]
Interest trade receivable percentage	100.00%
Receivables disposed of	$ 35.0	$ 45.0
Accounts payable, third party programs	130.0	105.0
Retained earnings	$ 2,973.0	$ 2,797.2	$ 49.2
Number of reporting units | reporting_unit	7