Investments - (Schedule of Allowance for Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Allowance for credit losses as of the beginning of the period	$ 3.2	$ 7.1
Additional credit losses on investments for which an allowance was previously recognized	4.1	0.0
Recoveries	(0.1)	0.0
Allowance for credit losses as of the end of the period	$ 7.2	$ 7.1