Segment Information - Schedule of segment reporting information, by segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
less: Loss and loss adjustment expenses, net	$ 85.4	$ 65.9
Other insurance expense	26.1	17.3
Sales and marketing	43.2	30.4
Technology development	22.0	20.9
General and administrative	35.9	29.8
Depreciation and amortization	4.5	5.0
Income tax expense	1.0	2.1
Net loss	(62.4)	(47.3)
Reportable Segment
Segment Reporting Information [Line Items]
Total revenue	151.2	119.1
less: Loss and loss adjustment expenses, net	85.4	65.9
Other insurance expense	26.1	17.3
Sales and marketing	5.1	10.6
Advertising expenses	38.1	19.8
Technology development	22.0	20.9
General and administrative	28.1	24.2
Interest expense	3.3	0.6
Depreciation and amortization	4.5	5.0
Income tax expense	1.0	2.1
Net loss	$ (62.4)	$ (47.3)