INVESTMENTS IN EQUITY INVESTEES - Equity Investees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Gross margin	$ 462.1	$ 432.7	$ 359.2
Net income	185.6	171.3	170.4
Total equity, royalty and interest income from investees	34.3	33.6	28.0
Current assets	755.0	693.0
Current liabilities	(344.9)	(375.0)
Atmus share of net assets	84.9	85.7	78.9
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net sales	456.7	435.2	392.5
Gross margin	183.0	170.0	136.3
Net income	57.4	56.2	38.4
Atmus share of net income	28.1	27.6	22.7
Royalty and interest income	6.2	6.0	5.3
Current assets	173.8	182.5	157.9
Non-current assets	89.6	87.4	82.0
Current liabilities	(85.8)	(89.1)	(75.9)
Non-current liabilities	(5.3)	(4.7)	(7.3)
Net assets	$ 172.3	$ 176.1	$ 156.7