Basis of Presentation and Description of Business - Changes to Annual Results: Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020		Jan. 01, 2020	Dec. 31, 2019	Feb. 07, 2019	Dec. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total Assets as of December 31, 2020	$ 9,997.2	$ 9,220.3	[1]
Total Liabilities as of December 31, 2020	6,251.9	5,636.4	[1]
Treasury Stock, 873,217 shares at December 31, 2021 and 465,903 shares at December 31, 2020	$ 3,745.3	3,583.9	[1]	$ 1,577.3	$ 1,577.3	$ (681.9)	$ (13.5)
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total Assets as of December 31, 2020		9,219.4
Total Liabilities as of December 31, 2020		5,641.7
Treasury Stock, 873,217 shares at December 31, 2021 and 465,903 shares at December 31, 2020		3,577.7		1,577.7
Increase (Decrease)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total Assets as of December 31, 2020		0.9
Total Liabilities as of December 31, 2020		(5.3)
Treasury Stock, 873,217 shares at December 31, 2021 and 465,903 shares at December 31, 2020		$ 6.2		$ (0.4)

[1] See discussion in Note 1 - Basis of Presentation and Description of Business for further detail regarding the elimination of the International lag reporting.