ACQUISITIONS AND INVESTMENTS - Luxx Lighting (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
	Dec. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Common shares, stated value per share (USD per share)		$ 0.01	$ 0.01
Goodwill		$ 254.0	$ 605.2	$ 544.1
Minimum
Business Acquisition [Line Items]
Intangible assets amortization period		3 years
Maximum
Business Acquisition [Line Items]
Intangible assets amortization period		25 years
Hawthorne
Business Acquisition [Line Items]
Goodwill		$ 0.0	$ 350.2	$ 305.5
Luxx Lighting, Inc. | Hawthorne
Business Acquisition [Line Items]
Total consideration transferred	$ 213.2
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	0.1
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 21.0
Inventory and accounts receivable acquired	32.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	5.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(24.2)
Finite-lived intangible assets acquired	47.3
Goodwill	$ 151.6
Luxx Lighting, Inc. | Hawthorne | Minimum
Business Acquisition [Line Items]
Intangible assets amortization period	5 years
Luxx Lighting, Inc. | Hawthorne | Maximum
Business Acquisition [Line Items]
Intangible assets amortization period	25 years