Commitments and Contingencies - Legal Claims and Insurance (Details) - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Rollforward of reserves for legal claims
Reserves for legal claims, beginning of period	$ 729.1	$ 577.5
Increase in reserves	58.7	55.7
Payments	(19.5)	(16.1)
Reserves for legal claims, end of period	$ 768.3	$ 617.1

Amount of loss contingency liability.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-1

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-10

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- Definition

Amount of increase (decrease) in loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-1

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- Definition

Amount of cash outflow reducing loss contingency liability.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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