BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Policy Acquisition Costs (Details) $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, January 1	$ 18.0	$ 6.7
Acquisition costs deferred	32.3	28.5
Amortization expense	(23.8)	(20.4)
Balance, September 30	$ 26.5	$ 14.8
Number of reportable segments | segment	1