v3.24.1.u1
Consolidated Investment Products - Schedule of Financial Instruments of CIPs not Measured at Fair Value (Details) - USD ($)
$ in Millions
Mar. 31, 2024
Sep. 30, 2023
Carrying Value [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents $ 3,300.2 $ 3,686.4
Financial Liability [Abstract]    
Debt of CLOs1 3,041.0 3,052.8
Carrying Value [Member] | CIPs [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 275.8 363.7
Financial Liability [Abstract]    
Short-Term Debt 15.0  
Other debt   21.8
Estimated Fair Value [Member] | Level 1 [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 3,300.2 3,686.4
Estimated Fair Value [Member] | Level 2 [Member]    
Financial Liability [Abstract]    
Debt of CLOs1 2,552.1 2,419.4
Estimated Fair Value [Member] | CIPs [Member] | Level 1 [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 275.8 363.7
Estimated Fair Value [Member] | CIPs [Member] | Level 3 [Member]    
Financial Liability [Abstract]    
Short-Term Debt 15.0  
Other debt   8.6
Receivables 1,449.6 1,348.4
Debt of CLOs1 3,041.0 3,052.8
CIPs [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 824.1 716.0
Receivables 185.6 166.7
Financial Liability [Abstract]    
Debt of CLOs1 9,131.0 8,231.8
Short-Term Debt 15.0  
Other debt   21.8
Collateralized loan obligations [Member] | Carrying Value [Member] | CIPs [Member]    
Financial Liability [Abstract]    
Debt of CLOs1 [1] 9,116.0 8,210.0
Collateralized loan obligations [Member] | Estimated Fair Value [Member] | CIPs [Member] | Level 2 [Member]    
Financial Liability [Abstract]    
Debt of CLOs1 [1] 8,867.4 8,013.2
Collateralized loan obligations [Member] | CIPs [Member]    
Financial Liability [Abstract]    
Debt of CLOs1 $ 9,116.0 $ 8,210.0
[1] Substantially all was Level 2.