CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue
Net earned premium	$ 13.8	$ 25.3
Ceding commission income	9.0	0.0
Net investment income	0.2	0.9
Commission and other income	0.5	0.0
Total revenue	23.5	26.2
Expense
Loss and loss adjustment expense, net	16.5	18.2
Other insurance expense	4.8	3.3
Sales and marketing	29.1	19.2
Technology development	7.1	3.5
General and administrative	14.1	18.2
Total expense	71.6	62.4
Loss before income taxes	(48.1)	(36.2)
Income tax expense	0.9	0.3
Net loss	(49.0)	(36.5)
Other comprehensive income, net of tax
Unrealized gain on investments	0.1	0.0
Foreign currency translation adjustment	0.7	0.0
Comprehensive loss	$ (48.2)	$ (36.5)
Earnings Per Share [Abstract]
Net loss per share attributable to common stockholders—basic (usd per share)	$ (0.81)	$ (3.16)
Net loss per share attributable to common stockholders—diluted (usd per share)	$ (0.81)	$ (3.16)
Weighted average common shares outstanding—basic (shares)	60,218,652	11,542,042
Weighted average common shares outstanding—diluted (shares)	60,218,652	11,542,042