Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 127.4	$ 109.0	$ 247.3	$ 214.7
Management fees
Disaggregation of Revenue [Line Items]
Management fee revenue	122.3	105.5	235.2	207.7
Management fees | Quant & Solutions | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	92.9	79.5	178.8	156.8
Management fees | Quant & Solutions | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 29.4	$ 26.0	$ 56.4	$ 50.9