Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 123.1	$ 107.3	$ 337.8	$ 295.4
Management fees
Disaggregation of Revenue [Line Items]
Management fee revenue	112.1	95.3	319.8	278.7
Management fees | Quant & Solutions | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	85.6	72.0	242.4	209.3
Management fees | Quant & Solutions | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 26.5	$ 23.3	$ 77.4	$ 69.4