Business Segment Information - Narrative (Details) $ in Millions	12 Months Ended
Sep. 30, 2025 USD ($) segment	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment	3
Identifiable assets	$ 11,219.0	$ 11,232.0	$ 11,304.0
Sales	8,342.0	8,264.0	9,058.0
Intelligent Devices
Segment Reporting Information [Line Items]
Sales	3,756.0	3,804.0	4,098.0
U.S. Plans
Segment Reporting Information [Line Items]
Sales	$ 4,847.0	$ 4,612.0	$ 4,773.0
Customer Concentration Risk \| Revenue from Contract with Customer Benchmark \| Systems And Services
Segment Reporting Information [Line Items]
Portion of total sales from individual segment	20.00%	20.00%	20.00%
Corporate
Segment Reporting Information [Line Items]
Identifiable assets	$ 2,350.0	$ 2,105.0	$ 2,551.0
Corporate \| Shared by segments and used in operating activities
Segment Reporting Information [Line Items]
Identifiable assets	$ 274.0	$ 261.0	$ 241.0

Amount of asset recognized for present right to economic benefit.

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