Revenue - Schedule of Disaggregation of Revenue (Details) - Management fees - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 367.4	$ 433.3	$ 478.9
Quant & Solutions | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	279.1	313.1	249.7
Quant & Solutions | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	88.3	106.3	97.1
Liquid Alpha | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	0.0	0.0	82.0
Liquid Alpha | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	0.0	0.0	26.3
Other Segments | U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	0.0	10.2	17.1
Other Segments | Non-U.S.
Disaggregation of Revenue [Line Items]
Management fee revenue	$ 0.0	$ 3.7	$ 6.7