Consolidated Investment Products - Schedule of Valuation Techniques and Significant Unobservable Inputs used in Level 3 Fair Value Measurements (Details) $ in Millions | Dec. 31, 2024 USD ($) $ / shares | Sep. 30, 2024 USD ($) $ / shares |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | $ 806.9 | | $ 838 | |
CIPs [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | 11,897.4 | | 11,034.9 | |
Fair Value, Recurring [Member] | CIPs [Member] | Equity and debt securities [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | 2,684.9 | | 1,856.3 | |
Fair Value, Recurring [Member] | CIPs [Member] | Loans [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | 9,212.5 | | 9,178.6 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | 573.5 | | 550.1 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | $ 219.1 | | $ 214.5 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Private sale pricing [Member] | Minimum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | $ / shares | 0.01 | | 0.01 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Private sale pricing [Member] | Maximum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | $ / shares | 1,120 | | 1,000 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Private sale pricing [Member] | Weighted Average [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | $ / shares | 82.93 | [1] | 73.04 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Discount for lack of marketability [Member] | Minimum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.097 | | 0.098 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Discount for lack of marketability [Member] | Maximum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.133 | | 0.175 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market pricing [Member] | Discount for lack of marketability [Member] | Weighted Average [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.104 | | 0.115 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | $ 302.2 | | $ 291.6 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Discount for lack of marketability [Member] | Minimum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.058 | | 0.001 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Discount for lack of marketability [Member] | Maximum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.118 | | 0.104 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Discount for lack of marketability [Member] | Weighted Average [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.080 | | 0.081 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Revenue multiple [Member] | Minimum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 1.4 | | 1.2 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Revenue multiple [Member] | Maximum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 28.7 | | 22.8 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Market comparable companies [Member] | Revenue multiple [Member] | Weighted Average [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 11 | | 10.9 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Discounted cash flow [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | $ 52.2 | | $ 44 | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Discounted cash flow [Member] | Discount rate [Member] | Minimum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.063 | | | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Discounted cash flow [Member] | Discount rate [Member] | Maximum [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.064 | | | |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Equity and debt securities [Member] | Discounted cash flow [Member] | Discount rate [Member] | Weighted Average [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Investments, measurement input | 0.063 | | 0.068 | [1] |
Fair Value, Recurring [Member] | CIPs [Member] | Level 3 [Member] | Loans [Member] | | | | |
Schedule Of Consolidated Investment Products [Line Items] | | | | |
Total investments, at fair value | $ 0.2 | | $ 0.5 | |
|
[1] Based on the relative fair value of the instruments. |