Unconsolidated Investments - Income From Unconsolidated Investments (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Income from unconsolidated investments - operating performance	$ 14.4	$ 8.8
Income from unconsolidated investments - realized (losses) gains	(0.6)	2.4
Income from unconsolidated investments - fair value (losses) gains	(1.9)	28.3
Income from unconsolidated investments - performance fees	(1.0)	2.2
Income from unconsolidated investments	$ 10.9	$ 41.7

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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