Investments - Schedule of Performance Allocations Included in Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Total	$ 799.1	$ 622.9	$ 2,058.6
Corporate Private Equity
Schedule of Investments [Line Items]
Total	248.8	291.4	1,629.6
Real Assets
Schedule of Investments [Line Items]
Total	301.6	148.4	265.2
Global Credit
Schedule of Investments [Line Items]
Total	38.5	9.1	21.3
Investment Solutions
Schedule of Investments [Line Items]
Total	$ 210.2	$ 174.0	$ 142.5