v3.25.2
Assets and Liabilities Held for Sale and Discontinued Operations - Narrative (Details) - USD ($)
$ in Millions
Jul. 31, 2025
Jun. 30, 2025
Sep. 30, 2024
Jul. 31, 2024
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Assets   $ 43,393 $ 42,695  
Johnson Controls - Hitachi Air Conditioning Holding (UK) Ltd        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Ownership percentage   60.00%   60.00%
Johnson Controls - Hitachi Air Conditioning Holding (UK) Ltd | Hitachi Global Life Solutions, Inc.        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Ownership percentage   40.00%   40.00%
Residential and Light Commercial HVAC Business        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Proceeds from divestiture of businesses       $ 6,700
Residential and Light Commercial HVAC Business | Johnson Controls International PLC And Hitachi Global Life Solutions, Inc.        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Proceeds from divestiture of businesses       $ 8,100
Residential and Light Commercial HVAC Business | Johnson Controls International PLC And Hitachi Global Life Solutions, Inc. | Subsequent Event        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Proceeds from divestiture of businesses $ 5,000      
Disposal Group, Held-for-sale, Not Discontinued Operations | ADT Mexico Business        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Assets   $ 122    
Liabilities   $ 23