Goodwill and Other Intangible Assets - Schedule of Acquisition Date Fair Values, Accumulated Amortization and Net Carrying Values for Other Intangibles Assets and Goodwill, By Company (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	$ 201.8	$ 142.3
Goodwill, net carrying value	201.8	142.3
Total Equity Including Noncontrolling Interest
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	407.0	347.5
Other intangible assets, accumulated amortization	9.0	7.0
Total goodwill and other intangible assets	398.0	340.5
Non-controlling interest
Acquired Finite-Lived Intangible Assets [Line Items]
Total goodwill and other intangible assets	103.4	91.8
Total
Acquired Finite-Lived Intangible Assets [Line Items]
Total goodwill and other intangible assets	294.6	248.7
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	205.2	205.2
Other intangible assets, accumulated amortization	9.0	7.0
Other intangible assets, net carrying value	196.2	198.2
Ark
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	116.8	116.8
Goodwill, net carrying value	116.8	116.8
Ark | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	175.7	175.7
Other intangible assets, accumulated amortization	0.0	0.0
Other intangible assets, net carrying value	175.7	175.7
Asset Management (Kudu)
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	7.6	7.6
Goodwill, net carrying value	$ 7.6	7.6
Asset Management (Kudu) | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	7 years
Other intangible assets, acquisition date fair value	$ 2.2	2.2
Other intangible assets, accumulated amortization	1.1	0.9
Other intangible assets, net carrying value	1.1	1.3
Other Operations (1)
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	77.4	17.9
Goodwill, net carrying value	77.4	17.9
Other intangible assets, acquisition date fair value	27.3	27.3
Other intangible assets, accumulated amortization	7.9	6.1
Other intangible assets, net carrying value	$ 19.4	21.2
Other Operations (1) | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	17 years 6 months
Other intangible assets, acquisition date fair value	$ 8.2	8.2
Other intangible assets, accumulated amortization	2.0	1.5
Other intangible assets, net carrying value	$ 6.2	6.7
Other Operations (1) | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	13 years
Other intangible assets, acquisition date fair value	$ 18.8	18.8
Other intangible assets, accumulated amortization	5.7	4.5
Other intangible assets, net carrying value	$ 13.1	14.3
Other Operations (1) | Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	5 years 3 months 18 days
Other intangible assets, acquisition date fair value	$ 0.3	0.3
Other intangible assets, accumulated amortization	0.2	0.1
Other intangible assets, net carrying value	$ 0.1	$ 0.2