Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Right-of-use assets (Note 22)	$ 15.2	$ 17.4
Prepaid expenses	8.9	12.0
Investment income due and accrued	6.7	5.5
Receivable from carriers	3.8	1.7
Security deposits	1.1	1.1
Ceding commission receivable	0.0	19.4
Income tax receivable	0.0	1.5
Other	6.7	5.2
Total other assets	$ 42.4	$ 63.8
Operating lease, right-of-use asset, statement of financial position	Total other assets	Total other assets