Segment Reporting - Adjustments for Performance Fees, Performance Fee Related Compensation and Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Investment income	$ 394.6	$ 2,218.4	$ 1,424.4	$ 4,183.6
Performance revenues related compensation expense	207.0	994.0	577.7	1,860.6
Net performance revenues	130.9	1,086.7	470.4	2,006.2
Adjustments
Segment Reporting Information [Line Items]
Performance revenues related compensation expense	42.0	(777.4)	(210.4)	(1,551.6)
Net performance revenues	140.0	(849.3)	(81.5)	(1,692.8)
Total Reportable Segments
Segment Reporting Information [Line Items]
Performance revenues related compensation expense	249.0	216.6	367.3	309.0
Net performance revenues	270.9	237.4	388.9	313.4
Performance allocations
Segment Reporting Information [Line Items]
Investment income	337.9	2,080.7	1,048.1	3,866.8
Performance allocations \| Adjustments
Segment Reporting Information [Line Items]
Investment income	182.0	(1,626.7)	(291.9)	(3,244.4)
Performance allocations \| Total Reportable Segments
Segment Reporting Information [Line Items]
Investment income	519.9	454.0	756.2	622.4
Principal investment income
Segment Reporting Information [Line Items]
Investment income	56.7	137.7	376.3	316.8
Principal investment income \| Adjustments
Segment Reporting Information [Line Items]
Investment income	(12.9)	(99.9)	(306.2)	(249.0)
Principal investment income \| Total Reportable Segments
Segment Reporting Information [Line Items]
Investment income	$ 43.8	$ 37.8	$ 70.1	$ 67.8