Basis of Presentation (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Mar. 01, 2020	Jan. 01, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Held-to-maturity, Allowance for Credit Loss							$ 0.0
Proceeds from Interest Received	$ 10.0	$ 4.0
Accrued Investment Income Receivable	10.5
Accounts Receivable, Allowance for Credit Loss	145.5	75.0	$ 146.1				73.0	$ 74.2		$ 73.0
Off-Balance Sheet, Credit Loss, Liability							0.0
Deferred tax liability, net	(29.8)						(26.7)
Retained Earnings (Accumulated Deficit)	938.9						953.6
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss						$ 0.0
Accounts Receivable, Allowance for Credit Loss				$ 2.3		103.0	0.0		$ 0.0	0.0
Off-Balance Sheet, Credit Loss, Liability	1.2	$ 0.0	$ 3.5		$ 0.0	2.3	$ 1.2	$ 0.0	$ 0.0	$ 0.0
Deferred tax liability, net						(18.5)
Retained Earnings (Accumulated Deficit)						929.5
Cumulative Effect, Period of Adoption, Adjustment [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss						0.0
Accounts Receivable, Allowance for Credit Loss	$ 30.0					30.0
Off-Balance Sheet, Credit Loss, Liability						2.3
Deferred tax liability, net						(8.2)
Retained Earnings (Accumulated Deficit)						$ (24.1)