Claims, Lawsuits And Other Contingencies (Details) - Jardine Lloyd Thompson Group plc case in Thousands, £ in Millions, $ in Millions	48 Months Ended
Dec. 31, 2018 case	Sep. 30, 2021 GBP (£)	Sep. 30, 2021 USD ($)	Dec. 31, 2020 GBP (£)	Dec. 31, 2020 USD ($)	Feb. 28, 2019 GBP (£)	Feb. 28, 2019 USD ($)
Loss Contingencies [Line Items]
Individual cases analyzed	14
Loss contingency accrual		£ 25	$ 34	£ 155	$ 210	£ 59	$ 77

Amount of loss contingency liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant