Stock-based Compensation - Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 16,900,000	$ 15,400,000	$ 47,200,000	$ 45,600,000
Warrant shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,000,000.0	900,000	4,500,000	1,500,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	7,700,000	9,100,000	22,500,000	29,400,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	7,200,000	5,400,000	20,200,000	14,700,000
Loss and loss adjustment expense, net
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	500,000	800,000	1,500,000	2,200,000
Other insurance expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	700,000	600,000	1,900,000	1,600,000
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,000,000.0	1,900,000	7,600,000	4,600,000
Technology development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	6,600,000	6,400,000	19,400,000	19,400,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,100,000	$ 5,700,000	$ 16,800,000	$ 17,800,000