Note 1 - Description of the Business	12 Months Ended
Dec. 31, 2024
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Note 1 — Description of the Business As used herein, “JHG,” “we,” “us,” “our” and similar terms refer to Janus Henderson Group plc and its subsidiaries, unless indicated otherwise. JHG is an independent global asset manager, specializing in active investment across all major asset classes. We actively manage a broad range of investment products for institutional and retail investors across four capabilities: Equities, Fixed Income, Multi-Asset and Alternatives. JHG is a public limited company incorporated in Jersey, Channel Islands, and is tax-resident and domiciled in the UK. Our common stock is traded on the NYSE.

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480424/946-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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