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Claims, Lawsuits, and Other Contingencies - Legal Narrative (Details) £ in Millions, $ in Millions					1 Months Ended				12 Months Ended
	Sep. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 06, 2018 USD ($)	Oct. 03, 2017 NZD ($)	Apr. 30, 2021 GBP (£) plaintiff	Aug. 31, 2020 USD ($) plaintiff	Nov. 30, 2019 USD ($) defendant	Nov. 30, 2018 USD ($)	Dec. 31, 2016 USD ($)	Sep. 16, 2020 USD ($)	Apr. 27, 2018 USD ($)
Aviation and Aerospace Broking Industry
Legal, Guarantees and Indemnifications
Revenue									$ 100,000,000
Christchurch City Council | Pending Litigation
Legal, Guarantees and Indemnifications
Damages sought		$ 180,000,000		$ 320
Aon Hewitt Investment Consulting Inc
Legal, Guarantees and Indemnifications
Investment losses suffered by plaintiff											$ 200,000,000
Fatal Plain Crash In November 2016 | Pending Litigation
Legal, Guarantees and Indemnifications
Damages sought	$ 31,000,000				£ 29	$ 844,000,000		$ 16,000,000
Number of defendants | defendant							3
Damages sought option 1							$ 300,000,000
Damages sought option 2							50,000,000
Damages sought option 3							$ 25,000,000
Loss contingency, number of plaintiffs | plaintiff					16	43
NEBC
Legal, Guarantees and Indemnifications
Investment losses suffered by plaintiff										$ 2,000,000,000
Minimum
Legal, Guarantees and Indemnifications
Estimate of possible loss	0
Minimum | Pilkington North America, Inc.
Legal, Guarantees and Indemnifications
Damages sought			$ 45,000,000
Maximum
Legal, Guarantees and Indemnifications
Estimate of possible loss	$ 100,000,000
Maximum | Pilkington North America, Inc.
Legal, Guarantees and Indemnifications
Damages sought			85,000,000
Damages awarded			$ 15,000,000

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