Unpaid Loss and Loss Adjustment Expense - Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid loss and LAE at beginning of period	$ 46.3	$ 28.2
Less: Reinsurance recoverable at beginning of period	36.3	18.5
Net unpaid loss and LAE at beginning of period	10.0	9.7
Add: Incurred losses and LAE, net of reinsurance, related to:
Current year	73.2	54.8
Prior years	(1.3)	(0.1)
Total incurred	71.9	54.7	$ 45.8
Deduct: Paid losses and LAE, net of reinsurance, related to:
Current year	49.2	44.6
Prior years	7.5	9.8
Total paid	56.7	54.4
Foreign currency translation gain (loss)	0.0	0.0
Unpaid loss and LAE, net of reinsurance recoverable, at end of period	25.2	10.0	9.7
Reinsurance recoverable at end of period	72.7	36.3	18.5
Unpaid loss and LAE, gross of reinsurance recoverable, at end of period	$ 97.9	$ 46.3	$ 28.2