Business Segment Information - Sales and Operating Results (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Sales and operating results of reportable segments
Sales	$ 1,848.2	$ 1,394.0	$ 5,189.6	$ 4,759.8
Purchase accounting depreciation and amortization	(12.9)	(10.6)	(37.7)	(30.1)
Corporate and other	(29.2)	(26.4)	(87.6)	(76.9)
Non-operating pension and postretirement benefit cost	(34.3)	(8.6)	(48.3)	(25.9)
Gain on investments	43.3	175.5	624.6	101.7
Legal Settlement	0.0	0.0	70.0	0.0
Interest (expense) income - net	(22.1)	(24.8)	(67.2)	(72.3)
Income before income taxes	313.5	334.5	1,521.9	836.5
Operating Segments
Sales and operating results of reportable segments
Sales	1,848.2	1,394.0	5,189.6	4,759.8
Segment operating earnings	368.7	229.4	1,068.1	940.0
Intelligent Devices
Sales and operating results of reportable segments
Sales	882.9	659.9	2,454.8	2,221.5
Intelligent Devices | Operating Segments
Sales and operating results of reportable segments
Sales	882.9	659.9	2,454.8	2,221.5
Segment operating earnings	193.6	111.6	535.8	452.9
Software & Control
Sales and operating results of reportable segments
Sales	509.6	364.7	1,452.9	1,265.4
Software & Control | Operating Segments
Sales and operating results of reportable segments
Sales	509.6	364.7	1,452.9	1,265.4
Segment operating earnings	128.3	82.1	411.2	359.3
Lifecycle Services
Sales and operating results of reportable segments
Sales	455.7	369.4	1,281.9	1,272.9
Lifecycle Services | Operating Segments
Sales and operating results of reportable segments
Sales	455.7	369.4	1,281.9	1,272.9
Segment operating earnings	$ 46.8	$ 35.7	$ 121.1	$ 127.8