Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 107.3	$ 86.8	$ 295.4	$ 294.5
Management fees
Disaggregation of Revenue [Line Items]
Management fee revenue	95.3	85.7	278.7	281.4
Management fees | Quant & Solutions | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	72.0	64.9	209.3	213.1
Management fees | Quant & Solutions | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 23.3	$ 20.8	$ 69.4	$ 68.3