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, 2023	Dec. 31, 2022
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	$ 168.8	$ 176.5
Goodwill	168.8	176.5
Total Equity Including Noncontrolling Interest
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, accumulated amortization	14.0	12.2
Total goodwill and other intangible assets	387.6	404.6
Total goodwill and other intangible assets	373.6	392.4
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, acquisition date fair value	218.8	228.1
Other intangible assets, accumulated amortization	14.0	12.2
Other intangible assets, net carrying value	204.8	215.9
Ark
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	116.8	116.8
Goodwill	116.8	116.8
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	$ 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	1.4	1.2
Other intangible assets, net carrying value	0.8	1.0
Other Operations
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, acquisition date fair value	44.4	52.1
Goodwill	44.4	52.1
Other intangible assets, acquisition date fair value	40.9	50.2
Other intangible assets, accumulated amortization	12.6	11.0
Other intangible assets, net carrying value	28.3	39.2
Total goodwill and other intangible assets	$ 72.7	91.3
Other Operations | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	13 years 3 months 18 days
Other intangible assets, acquisition date fair value	$ 13.3	17.9
Other intangible assets, accumulated amortization	3.3	3.0
Other intangible assets, net carrying value	$ 10.0	14.9
Other Operations | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, weighted average useful life (in years)	11 years
Other intangible assets, acquisition date fair value	$ 24.8	29.5
Other intangible assets, accumulated amortization	8.5	7.5
Other intangible assets, net carrying value	$ 16.3	22.0
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	2.8
Other intangible assets, accumulated amortization	0.8	0.5
Other intangible assets, net carrying value	$ 2.0	$ 2.3