REINSURANCE- Schedule of Comprehensive Loss For Reinsurance (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Premiums written:
Direct	$ 250.1	$ 128.1	$ 523.0	$ 251.9
Assumed	58.1	16.9	115.9	27.8
Ceded	(44.6)	(67.2)	(91.3)	(137.1)
Net premiums written	263.6	77.8	547.6	142.6
Premiums earned:
Direct	252.7	120.2	481.1	240.3
Assumed	55.3	11.3	101.9	21.3
Ceded	(46.4)	(67.6)	(91.1)	(137.7)
Net premiums earned	261.6	63.9	491.9	123.9
Losses and LAE incurred:
Direct	173.6	90.5	335.8	190.3
Assumed	45.1	8.7	76.6	16.4
Ceded	(28.4)	(39.7)	(55.7)	(83.9)
Net losses and LAE incurred	$ 190.3	$ 59.5	$ 356.7	$ 122.8

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

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