Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 119.9	$ 105.7
Management fees
Disaggregation of Revenue [Line Items]
Management fee revenue	112.9	102.2
Management fees | Quant & Solutions | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	85.9	77.3
Management fees | Quant & Solutions | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 27.0	$ 24.9