v3.26.1
INFORMATION ABOUT RECEIVABLES, REVENUES, AND SERVICES - Schedule of Revenues From Advisory Services (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Revenue and Services [Line Items]        
Net revenues $ 1,907.4 $ 1,723.3 $ 3,764.4 $ 3,487.2
Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues 1,744.8 1,567.6 3,427.8 3,166.0
Investment advisory fees | Assets under management        
Revenue and Services [Line Items]        
Net revenues 1,837,700.0 1,588,800.0 1,806,900.0 1,604,500.0
Performance-based advisory fees        
Revenue and Services [Line Items]        
Net revenues 6.5 6.4 14.0 16.8
Capital allocation-based income        
Revenue and Services [Line Items]        
Net revenues 11.9 (0.4) 40.0 (1.6)
Administrative, distribution, servicing, and other fees        
Revenue and Services [Line Items]        
Net revenues 144.2 149.7 282.6 306.0
Equity | Investment advisory fees | Assets under management        
Revenue and Services [Line Items]        
Net revenues 886,600.0 784,400.0 873,900.0 805,300.0
Fixed income, including money market | Investment advisory fees | Assets under management        
Revenue and Services [Line Items]        
Net revenues 219,000.0 198,000.0 216,400.0 194,800.0
Multi-asset | Investment advisory fees | Assets under management        
Revenue and Services [Line Items]        
Net revenues 671,200.0 552,500.0 656,600.0 551,100.0
Alternatives | Investment advisory fees | Assets under management        
Revenue and Services [Line Items]        
Net revenues 60,900.0 53,900.0 60,000.0 53,300.0
Investment advisory fees | Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues 1,744.8 1,567.6 3,427.8 3,166.0
Investment advisory fees | Equity | Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues 1,011.9 923.6 1,986.6 1,882.8
Investment advisory fees | Fixed income, including money market | Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues 113.5 105.5 225.3 209.1
Investment advisory fees | Multi-asset | Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues 529.5 455.9 1,038.6 910.6
Investment advisory fees | Alternatives | Investment advisory fees        
Revenue and Services [Line Items]        
Net revenues $ 89.9 $ 82.6 $ 177.3 $ 163.5