INVESTMENTS - Carrying Amounts of Investments (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 414.0	$ 408.4
Gross Unrealized Gains	4.0	7.3
Gross Unrealized Losses	(1.3)	(0.4)
Fair Value	416.6	415.3
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2.2	0.5
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Fair Value	2.2	0.5
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1.8	2.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Fair Value	1.8	2.6
Municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4.8	4.9
Gross Unrealized Gains	0.0	0.1
Gross Unrealized Losses	0.0	0.0
Fair Value	4.9	5.0
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	170.1	163.3
Gross Unrealized Gains	1.9	3.8
Gross Unrealized Losses	(0.5)	0.0
Fair Value	171.6	167.0
Mortgage and other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	235.0	237.1
Gross Unrealized Gains	2.0	3.4
Gross Unrealized Losses	(0.9)	(0.3)
Fair Value	$ 236.2	$ 240.1