PENSION AND POST-RETIREMENT BENEFITS - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Net periodic benefit costs:
Total net periodic benefit costs	$ 1.3	$ 1.5	$ 3.6	$ 4.2	$ 4.0
Pension Plans
Net periodic benefit costs:
Service cost	0.4	0.5	1.1	1.3
Interest cost	2.3	3.8	6.9	11.2
Expected return on plan assets	(4.9)	(5.7)	(14.8)	(17.1)
Amortization of actuarial loss	3.3	2.7	9.9	8.3
Total net periodic benefit costs prior to allocation	1.1	1.3	3.1	3.7
Portion allocated to Revlon Holdings	0.0	0.0	(0.1)	(0.1)
Total net periodic benefit costs	1.1	1.3	3.0	3.6
Other Post-Retirement Benefit Plans
Net periodic benefit costs:
Service cost	0.0	0.0	0.0	0.0
Interest cost	0.0	0.1	0.1	0.3
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of actuarial loss	0.2	0.1	0.5	0.3
Total net periodic benefit costs prior to allocation	0.2	0.2	0.6	0.6
Portion allocated to Revlon Holdings	0.0	0.0	0.0	0.0
Total net periodic benefit costs	$ 0.2	$ 0.2	$ 0.6	$ 0.6