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Note 16 - Retirement Benefit Plans - Schedule of Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Retirement benefit asset, net	$ 70.3	$ 87.6
Pension Plan [Member]
Retirement benefit asset, net	70.3	87.6
Janus Henderson Group unapproved pension scheme	(2.0)	(2.3)
Net retirement benefit asset recognized in the Consolidated Balance Sheets	$ 68.3	$ 85.3

X

- Definition

Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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