v3.22.2.2
ACQUISITIONS AND INVESTMENTS - Hydro-Logic (Details) - USD ($)
$ in Millions
12 Months Ended
Aug. 27, 2021
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2020
Business Acquisition [Line Items]        
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
Hawthorne | Hydro-Logic Purification Systems, Inc.        
Business Acquisition [Line Items]        
Total consideration transferred $ 65.3      
Inventory and accounts receivable acquired 4.5      
Other assets acquired 1.6      
Other liabilities assumed 2.6      
Finite-lived intangible assets acquired 23.1      
Goodwill $ 38.7      
Hawthorne | Hydro-Logic Purification Systems, Inc. | Minimum        
Business Acquisition [Line Items]        
Intangible assets amortization period 5 years      
Hawthorne | Hydro-Logic Purification Systems, Inc. | Maximum        
Business Acquisition [Line Items]        
Intangible assets amortization period 15 years