Segment Reporting - Adjustments for Performance Fees, Performance Fee Related Compensation and Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Segment Reporting Information [Line Items]
Performance revenues	$ (616.7)	$ 159.8
Performance revenues related compensation expense	(367.9)	171.4
Performance revenues
Segment Reporting Information [Line Items]
Performance revenues	(681.1)	222.9
Performance revenues related compensation expense	(367.9)	171.4
Net performance revenues	(313.2)	51.5
Performance revenues \| Adjustments
Segment Reporting Information [Line Items]
Performance revenues	742.9	132.2
Performance revenues related compensation expense	409.2	56.3
Net performance revenues	333.7	75.9
Performance revenues \| Total Reportable Segments \| Global Segments
Segment Reporting Information [Line Items]
Performance revenues	61.8	355.1
Performance revenues related compensation expense	41.3	227.7
Net performance revenues	20.5	127.4
Principal investment income (loss)
Segment Reporting Information [Line Items]
Performance revenues	64.4	(63.1)
Principal investment income (loss) \| Adjustments
Segment Reporting Information [Line Items]
Performance revenues	(36.2)	93.1
Principal investment income (loss) \| Total Reportable Segments \| Global Segments
Segment Reporting Information [Line Items]
Performance revenues	$ 28.2	$ 30.0