Employee Benefit Plans Allocation of Plan Assets (Details) - UNITED KINGDOM	Sep. 30, 2021
Equity
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations, percentage	17.80%
Target plan assets allocation, percentage	0.00%
Index‑linked gilts
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations, percentage	76.00%
Target plan assets allocation, percentage	70.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations, percentage	6.20%
Target plan assets allocation, percentage	30.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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- Definition

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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