Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total	$ 6,686	$ 6,098	$ 12,754	$ 11,960
Products and systems
Disaggregation of Revenue [Line Items]
Total	5,083	4,617	9,639	9,037
Services
Disaggregation of Revenue [Line Items]
Total	1,603	1,481	3,115	2,923
Building Solutions North America
Disaggregation of Revenue [Line Items]
Total	2,520	2,227	4,887	4,379
Building Solutions North America | Products and systems
Disaggregation of Revenue [Line Items]
Total	1,554	1,343	3,005	2,642
Building Solutions North America | Services
Disaggregation of Revenue [Line Items]
Total	966	884	1,882	1,737
Building Solutions EMEA/LA
Disaggregation of Revenue [Line Items]
Total	1,031	958	2,006	1,917
Building Solutions EMEA/LA | Products and systems
Disaggregation of Revenue [Line Items]
Total	582	536	1,134	1,080
Building Solutions EMEA/LA | Services
Disaggregation of Revenue [Line Items]
Total	449	422	872	837
Building Solutions Asia Pacific
Disaggregation of Revenue [Line Items]
Total	667	623	1,313	1,298
Building Solutions Asia Pacific | Products and systems
Disaggregation of Revenue [Line Items]
Total	479	448	952	949
Building Solutions Asia Pacific | Services
Disaggregation of Revenue [Line Items]
Total	188	175	361	349
Global Products
Disaggregation of Revenue [Line Items]
Total	2,468	2,290	4,548	4,366
Global Products | Products and systems
Disaggregation of Revenue [Line Items]
Total	2,468	2,290	4,548	4,366
Global Products | HVAC
Disaggregation of Revenue [Line Items]
Total	1,757	1,658	3,197	3,141
Global Products | Fire & Security
Disaggregation of Revenue [Line Items]
Total	623	578	1,193	1,122
Global Products | Industrial Refrigeration
Disaggregation of Revenue [Line Items]
Total	88	54	158	103
Global Products | Services
Disaggregation of Revenue [Line Items]
Total	$ 0	$ 0	$ 0	$ 0