DISCONTINUED OPERATIONS - Results of Discontinued Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Operating and exit costs	$ 0.0	$ 1.3	$ 0.6
Impairment, restructuring and other charges (recoveries)	0.0	(3.1)	(35.8)
Write-down of contingent consideration receivable	12.2	0.0	0.0
Income (loss) from discontinued operations before income taxes	(12.2)	1.8	35.2
Income tax expense (benefit) from discontinued operations	(8.3)	0.1	11.7
Income (loss) from discontinued operations, net of tax	$ (3.9)	$ 1.7	$ 23.5