Investments - Investment Components of Accrued Performance Fees (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Accrued performance allocations	$ 8,100.3	$ 4,968.6
Maximum lag period for which the partnership investments in funds are valued	90 days	90 days
Global Private Equity
Segment Reporting Information [Line Items]
Accrued performance allocations	$ 6,485.7	$ 3,926.1
Global Credit
Segment Reporting Information [Line Items]
Accrued performance allocations	262.8	132.3
Global Investment Solutions
Segment Reporting Information [Line Items]
Accrued performance allocations	$ 1,351.8	$ 910.2