CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2022	Sep. 30, 2022	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Revenues:
Net premiums earned	$ 64.3	$ 68.6	$ 74.7	$ 78.3			$ 285.9		$ 310.3		$ 322.5
Net investment income	4.0	0.9	0.7	0.6			6.2		5.0		5.4
Gain (Loss) on Investments	(0.6)	0.0	(0.1)	1.2			0.5		2.4		0.3
Fee income	3.4	3.8	4.4	4.9			16.5		20.9		17.4
Other Income	0.2	0.4	0.7	0.4			1.7		6.8		1.2
Total revenues	71.3	73.7	80.4	85.4			310.8		345.4		346.8
Operating expenses:
Loss and loss adjustment expenses	77.7	80.9	95.7	96.7			351.0		392.3		362.8
Sales and marketing	3.2	8.1	21.4	15.3	$ 36.7	$ 44.8	48.0		270.2		139.7
Other insurance (benefit) expense	(2.3)	1.1	(7.8)	1.0			(8.0)		5.0		(1.8)
Technology and development	9.4	14.3	17.9	13.9			55.5		65.5		52.9
General and administrative	31.0	26.4	39.5	30.5	70.0	96.4	127.4		97.6		78.5
Total operating expenses	119.0	130.8	166.7	157.4	324.1	454.9	573.9		830.6		632.1
Operating loss	(47.7)	(57.1)	(86.3)	(72.0)	(158.3)	(215.4)	(263.1)		(485.2)		(285.3)
Interest expense	(10.6)	(9.3)	(9.2)	(5.5)			(34.6)		(20.0)		(77.7)
Loss on early extinguishment of debt							0.0		(15.9)		0.0
Loss before income tax expense	(58.3)	(66.4)	(95.5)	(77.5)	(173.0)	(239.4)	(297.7)		(521.1)		(363.0)
Income tax expense	0.0	0.0	0.0	0.0			0.0		0.0		0.0
Net loss	(58.3)	(66.4)	(95.5)	(77.5)	(173.0)	(239.4)	(297.7)		(521.1)		(363.0)
Other comprehensive (loss) income:
Changes in net unrealized (losses) gains on investments	1.1	(2.3)	(1.3)	(3.7)			(6.2)		(5.2)		5.0
Comprehensive loss	$ (57.2)	$ (68.7)	$ (96.8)	$ (81.2)	$ (178.0)	$ (246.7)	$ (303.9)		$ (526.3)		$ (358.0)
Loss per common share: basic (both Class A and B) (in dollars per share)	$ (4.13)	$ (4.71)	$ (6.77)	$ (5.54)	$ (12.36)	$ (17.10)	$ (21.11)	[1]	$ (37.76)	[1]	$ (86.43)	[1]
Loss per common share: diluted (both Class A and B) (in dollars per share)	$ (4.13)	$ (4.71)	$ (6.77)	$ (5.54)	$ (12.36)	$ (17.10)	$ (21.11)	[1]	$ (37.76)	[1]	$ (86.43)	[1]
Weighted-average common shares outstanding: basic (both Class A and B) (in shares)	14.1	14.1	14.1	14.0	14.0	14.0	14.1	[1]	13.8	[1]	4.2	[1]
Weighted-average common shares outstanding: diluted (both Class A and B) (in shares)	14.1	14.1	14.1	14.0	14.0	14.0	14.1	[1]	13.8	[1]	4.2	[1]

[1] Reflects the 1-for-18 reverse stock split that became effective August 12, 2022. Refer to Note 2, “Basis of Presentation and Summary of Significant Accounting Policies.”