Business Segment Information - Sales and Operating Results (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Sales and operating results of reportable segments
Sales	$ 1,857.3	$ 1,565.3
Purchase accounting depreciation and amortization	(26.1)	(11.7)
Corporate and other	(29.4)	(28.0)
Non-operating pension and postretirement benefit credit (cost)	4.4	(7.0)
Change in fair value of investments	7.6	390.4
Legal settlement	0.0	70.0
Interest expense, net	(29.1)	(22.3)
Income before income taxes	282.5	700.7
Gain (loss) related to litigation settlement		70.0	$ 70.0
Operating Segments
Sales and operating results of reportable segments
Sales	1,857.3	1,565.3
Segment operating earnings:	355.1	309.3
Intelligent Devices
Sales and operating results of reportable segments
Sales	900.3	721.7
Intelligent Devices \| Operating Segments
Sales and operating results of reportable segments
Sales	900.3	721.7
Segment operating earnings:	213.0	140.2
Software & Control
Sales and operating results of reportable segments
Sales	513.9	441.0
Software & Control \| Operating Segments
Sales and operating results of reportable segments
Sales	513.9	441.0
Segment operating earnings:	117.6	133.1
Lifecycle Services
Sales and operating results of reportable segments
Sales	443.1	402.6
Lifecycle Services \| Operating Segments
Sales and operating results of reportable segments
Sales	443.1	402.6
Segment operating earnings:	$ 24.5	$ 36.0

Equity Securities, FV-NI, Unrealized Gain (Loss), Loss On Investment

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General Corporate - Net

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