XML 127 R106.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Note 16 - Retirement Benefit Plans - Assumptions Used in Determining Benefit Obligation (Details) - Pension Plan [Member] | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Discount rate | 5.50% | 4.50%
Inflation — Retail Price Index (“RPI”) | 3.20% | 3.10%
Inflation — Consumer Price Index (“CPI”) | 2.50% | 2.50%
Pension increases (RPI capped at 5% per annum (“p.a.”)) | 3.10% | 3.00%
Pension increases (RPI capped at 2.5% p.a.) | 2.10% | 2.10%
Life expectancy of male aged 60 at accounting date (Year) | 29 years | 29 years 1 month 6 days
Life expectancy of male aged 60 in 15 years’ time (Year) | 30 years | 30 years 1 month 6 days

X
- Definition Percentage of inflation change in consumer price index in determining the defined benefit obligation based on key assumptions. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationConsumerPriceIndexInflation
Namespace Prefix: | jhg_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The average period that a person may expect to live at 15 years in time. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationLifeExpectancyOfMaleAged60At15YearsInTime
Namespace Prefix: | jhg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The average period that a person may expect to live at accounting date. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationLifeExpectancyOfMaleAged60AtAccountingDate
Namespace Prefix: | jhg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of increase in pension for which retail price index (RPI) capped at 2.5% p.a. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationPensionIncreaseRpiCappedAt25Pa
Namespace Prefix: | jhg_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of increase in pension for which retail price index (RPI) capped at 5% p.a. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationPensionIncreaseRpiCappedAt5Pa
Namespace Prefix: | jhg_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of inflation change in retail price index in determining the defined benefit obligation based on key assumptions. + References No definition available. + Details
Name: | jhg_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRetailPriceIndexInflation
Namespace Prefix: | jhg_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |