Supplemental Consolidated Cash and Cash Flow Information - Schedule of Cash and Restricted Cash (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021	[1]
Supplemental Cash Flow Elements [Abstract]
Cash	$ 33.1	$ 29.0	$ 42.2
Restricted cash	5.0	0.7	0.6
Total cash and restricted cash shown in the Consolidated Statements of Cash Flows	38.1	29.7	42.8	[1]	$ 133.7
Interest	33.5	30.1	18.2
Income taxes	22.1	$ 14.0	$ 8.6
Investments fixed maturity securities	$ 44.5

[1] Recast for the adoption of ASU 2018-12.