Segment Reporting - Adjustments for Performance Fees, Performance Fee Related Compensation and Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Investment income	$ 422.3	$ 1,134.9	$ 1,846.7	$ 5,318.5
Performance revenues related compensation expense	163.5	495.2	741.2	2,355.8
Net performance revenues	134.6	479.3	605.0	2,485.5
Adjustments
Segment Reporting Information [Line Items]
Performance revenues related compensation expense	210.2	(17.8)	(0.2)	(1,569.4)
Net performance revenues	256.5	54.2	175.0	(1,638.6)
Total Reportable Segments
Segment Reporting Information [Line Items]
Performance revenues related compensation expense	373.7	477.4	741.0	786.4
Net performance revenues	391.1	533.5	780.0	846.9
Performance allocations
Segment Reporting Information [Line Items]
Investment income	298.1	974.5	1,346.2	4,841.3
Performance allocations \| Adjustments
Segment Reporting Information [Line Items]
Investment income	466.7	36.4	174.8	(3,208.0)
Performance allocations \| Total Reportable Segments
Segment Reporting Information [Line Items]
Investment income	764.8	1,010.9	1,521.0	1,633.3
Principal investment income
Segment Reporting Information [Line Items]
Investment income	124.2	160.4	500.5	477.2
Principal investment income \| Adjustments
Segment Reporting Information [Line Items]
Investment income	(67.5)	(89.1)	(373.7)	(338.1)
Principal investment income \| Total Reportable Segments
Segment Reporting Information [Line Items]
Investment income	$ 56.7	$ 71.3	$ 126.8	$ 139.1