NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounts Receivable and Cash and Cash Equivalents (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in the allowance for doubtful accounts
Beginning balance	$ 2.3	$ 2.1
Bad debt expense (recovery)	0.0	0.7	$ (0.3)
Write-off, less recoveries	(0.5)	(0.5)
Ending balance	1.8	2.3	$ 2.1
Money market account balance	$ 53.8	$ 113.7