Investments - Components of Investment Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Investment income (loss)	$ 1,898.0	$ 6,721.9	$ 1,095.2
Performance allocations - realized
Schedule of Investments [Line Items]
Investment income (loss)	2,048.8	2,956.7	591.1
Performance allocations - unrealized
Schedule of Investments [Line Items]
Investment income (loss)	(721.3)	3,127.9	1,044.8
Performance allocations
Schedule of Investments [Line Items]
Investment income (loss)	1,327.5	6,084.6	1,635.9
Principal investment income (loss) from equity method investments - realized
Schedule of Investments [Line Items]
Investment income (loss)	73.1	266.2	135.5
Principal investment income (loss) from equity method investments - unrealized
Schedule of Investments [Line Items]
Investment income (loss)	546.4	290.8	(679.3)
Principal investment income (loss) from equity method investments
Schedule of Investments [Line Items]
Investment income (loss)	619.5	557.0	(543.8)
Principal investment income (loss) from investments in CLOs and other investments - realized
Schedule of Investments [Line Items]
Investment income (loss)	5.0	1.9	0.3
Principal investment income (loss) from investments in CLOs and other investments- unrealized
Schedule of Investments [Line Items]
Investment income (loss)	(54.0)	78.4	2.8
Principal investment income (loss) from investments in CLOs and other investments
Schedule of Investments [Line Items]
Investment income (loss)	$ (49.0)	$ 80.3	$ 3.1