REINSURANCE- Schedule of Comprehensive Income (Loss) For Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Premiums written:
Direct	$ 270.9	$ 192.7	$ 793.9	$ 444.6
Assumed	60.8	31.5	176.7	59.3
Ceded	(27.1)	(22.3)	(118.4)	(159.4)
Net premiums written	304.6	201.9	852.2	344.5
Premiums earned:
Direct	258.6	141.6	739.7	381.9
Assumed	58.4	18.2	160.3	39.5
Ceded	(37.7)	(59.8)	(128.8)	(197.5)
Net premiums earned	279.3	100.0	771.2	223.9
Losses and LAE incurred:
Direct	168.2	106.8	504.0	297.1
Assumed	39.1	13.4	115.7	29.8
Ceded	(22.8)	(34.4)	(78.5)	(118.3)
Net losses and LAE incurred	$ 184.5	$ 85.8	$ 541.2	$ 208.6

Liability For Unpaid Claims And Claims Adjustment Expense, Incurred Claims, Assumed

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