Other Liabilities and Accrued Expenses - Summary (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Other Liabilities Disclosure [Abstract]
Ceding commission payable	$ 23.5	$ 13.9
Lease liabilities	21.4	28.2
Uncertain tax position	17.9	13.3
Accrued advertising costs	15.8	6.2
Employee compensation	7.5	8.4
Premium taxes payable	6.1	5.9
Accrued professional fees	5.7	5.0
Payable to carriers	4.9	2.0
Advance premium	3.9	3.4
Reinsurance payable	1.9	0.8
Income taxes payable	1.8	1.2
Other payables	13.1	11.2
Total	$ 123.5	$ 99.5