Goodwill and Other Intangible Assets - Other Intangibles (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Other intangible assets
Amortized intangible assets, carrying amount	$ 1,188.0	$ 795.9
Amortized intangible assets, accumulated amortization	209.9	360.3
Amortized intangible assets, net	978.1	435.6
Total other intangible assets, carrying amount	1,231.7	839.6
Total other intangible assets, net	1,021.8	479.3
Software products
Other intangible assets
Amortized intangible assets, carrying amount	90.4	192.7
Amortized intangible assets, accumulated amortization	43.2	139.0
Amortized intangible assets, net	47.2	53.7
Customer relationships
Other intangible assets
Amortized intangible assets, carrying amount	595.9	351.3
Amortized intangible assets, accumulated amortization	75.4	92.5
Amortized intangible assets, net	520.5	258.8
Technology
Other intangible assets
Amortized intangible assets, carrying amount	420.8	165.8
Amortized intangible assets, accumulated amortization	71.7	84.0
Amortized intangible assets, net	349.1	81.8
Trademarks
Other intangible assets
Amortized intangible assets, carrying amount	73.8	71.7
Amortized intangible assets, accumulated amortization	13.3	31.3
Amortized intangible assets, net	60.5	40.4
Other
Other intangible assets
Amortized intangible assets, carrying amount	7.1	14.4
Amortized intangible assets, accumulated amortization	6.3	13.5
Amortized intangible assets, net	0.8	0.9
Trademarks
Other intangible assets
Allen-Bradley® trademark not subject to amortization	$ 43.7	$ 43.7