Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Right-of-Use assets (Note 21)	$ 26.4	$ 21.9
Ceding commission receivable	21.0	14.5
Prepaid expenses	14.0	10.6
Income tax receivable	5.0	0.0
Investment income due and accrued	3.7	3.4
Other	5.1	2.8
Total other assets	$ 75.2	$ 53.2
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total other assets	Total other assets