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	9 Months Ended
Sep. 30, 2022	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	$ 175.5	$ 142.3
Goodwill, net carrying value	175.5	142.3
Total Equity Including Noncontrolling Interest
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	403.6	347.5
Other intangible assets, accumulated amortization	10.4	7.0
Total goodwill and other intangible assets	393.2	340.5
Non-controlling interest
Acquired Finite-Lived Intangible Assets [Line Items]
Total goodwill and other intangible assets	103.1	91.8
Total
Acquired Finite-Lived Intangible Assets [Line Items]
Total goodwill and other intangible assets	290.1	248.7
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	228.1	205.2
Other intangible assets, accumulated amortization	10.4	7.0
Other intangible assets, net carrying value	217.7	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]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	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
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	51.1	17.9
Goodwill, net carrying value	51.1	17.9
Other intangible assets, acquisition date fair value	50.2	27.3
Other intangible assets, accumulated amortization	9.3	6.1
Other intangible assets, net carrying value	$ 40.9	21.2
Other Operations \| Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	15 years 10 months 24 days
Other intangible assets, acquisition date fair value	$ 17.9	8.2
Other intangible assets, accumulated amortization	2.4	1.5
Other intangible assets, net carrying value	$ 15.5	6.7
Other Operations \| Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	12 years 4 months 24 days
Other intangible assets, acquisition date fair value	$ 29.5	18.8
Other intangible assets, accumulated amortization	6.6	4.5
Other intangible assets, net carrying value	$ 22.9	14.3
Other Operations \| Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	12 years 1 month 6 days
Other intangible assets, acquisition date fair value	$ 2.8	0.3
Other intangible assets, accumulated amortization	0.3	0.1
Other intangible assets, net carrying value	$ 2.5	$ 0.2

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

9 Months Ended

Sep. 30, 2022

Dec. 31, 2021

Acquired Finite-Lived Intangible Assets [Line Items]

Goodwill, acquisition date fair value

$ 175.5

$ 142.3

Goodwill, net carrying value

175.5

142.3

Total Equity Including Noncontrolling Interest

Acquired Finite-Lived Intangible Assets [Line Items]