v3.25.1
Note 13 - Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Balance $ 4,718.1 $ 4,538.3
Total other comprehensive income (loss) 61.9 (45.2)
Less: other comprehensive loss (income) attributable to noncontrolling interests 9.4 (1.1)
Balance 4,826.5 4,427.4
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]    
Balance (387.9) (478.9)
Other comprehensive income (loss) 60.9 (23.6)
Reclassifications to net income(1) [1] 0.4 (22.0)
Total other comprehensive income (loss) 61.3 (45.6)
Less: other comprehensive loss (income) attributable to noncontrolling interests (9.4) 1.1
Balance (336.0) (523.4)
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]    
Balance (97.3) (84.7)
Other comprehensive income (loss) 0.0 0.0
Reclassifications to net income(1) [1] 0.6 0.4
Total other comprehensive income (loss) 0.6 0.4
Less: other comprehensive loss (income) attributable to noncontrolling interests 0.0 0.0
Balance (96.7) (84.3)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]    
Balance (485.2) (563.6)
Other comprehensive income (loss) 60.9 (23.6)
Reclassifications to net income(1) [1] 1.0 (21.6)
Total other comprehensive income (loss) 61.9 (45.2)
Less: other comprehensive loss (income) attributable to noncontrolling interests (9.4) 1.1
Balance $ (432.7) $ (607.7)
[1] Reclassifications to net income are primarily related to the release of accumulated foreign currency translation reserves during the period in which a JHG entity liquidated.