Segment Reporting - Revenue Adjustments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Unrealized principal investment income	$ 618.5	$ (534.4)	$ 673.1
Revenues	8,782.1	2,934.6	3,377.0
Reconciling Items
Segment Reporting Information [Line Items]
Unrealized performance revenues	3,155.6	1,031.0	267.8
Unrealized principal investment income	351.8	(556.2)	590.9
Adjustments related to expenses associated with investments in NGP Management and its affiliates	(13.7)	(15.3)	(16.2)
Tax expense associated with certain foreign performance revenues	0.2	0.5	0.3
Non-controlling interests and other adjustments to present certain costs on a net basis	159.6	96.6	117.5
Revenues	3,578.8	418.3	1,067.7
Consolidation, Eliminations
Segment Reporting Information [Line Items]
Revenues	(74.7)	(33.9)	(33.5)
Fortitude Re | Reconciling Items
Segment Reporting Information [Line Items]
Unrealized principal investment income	$ 0.0	$ (104.4)	$ 140.9