GOODWILL AND INTANGIBLE ASSETS - Changes in the Carrying Amount of Goodwill by Reporting Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Goodwill [Roll Forward]
Balance at beginning of period	$ 867.2	$ 627.2
Foreign currency impact	(22.2)	2.3
Balance at end of period	953.1	867.2
Armitage acquisition
Goodwill [Roll Forward]
Acquisitions		90.7
Rejuvenate acquisition
Goodwill [Roll Forward]
Acquisitions		147.0
Rejuvenate acquisition | Tradenames
Goodwill [Roll Forward]
Balance at end of period	119.1
Tristar acquisition
Goodwill [Roll Forward]
Acquisitions	108.1
HPC
Goodwill [Roll Forward]
Balance at beginning of period	0.0	0.0
Foreign currency impact	0.0	0.0
Balance at end of period	108.1	0.0
HPC | Armitage acquisition
Goodwill [Roll Forward]
Acquisitions		0.0
HPC | Rejuvenate acquisition
Goodwill [Roll Forward]
Acquisitions		0.0
HPC | Tristar acquisition
Goodwill [Roll Forward]
Acquisitions	108.1
GPC
Goodwill [Roll Forward]
Balance at beginning of period	524.6	431.6
Foreign currency impact	(22.2)	2.3
Balance at end of period	502.4	524.6
GPC | Armitage acquisition
Goodwill [Roll Forward]
Acquisitions		90.7
GPC | Rejuvenate acquisition
Goodwill [Roll Forward]
Acquisitions		0.0
GPC | Tristar acquisition
Goodwill [Roll Forward]
Acquisitions	0.0
H&G
Goodwill [Roll Forward]
Balance at beginning of period	342.6	195.6
Foreign currency impact	0.0	0.0
Balance at end of period	342.6	342.6
H&G | Armitage acquisition
Goodwill [Roll Forward]
Acquisitions		0.0
H&G | Rejuvenate acquisition
Goodwill [Roll Forward]
Acquisitions		$ 147.0
H&G | Tristar acquisition
Goodwill [Roll Forward]
Acquisitions	$ 0.0