Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
ROU lease assets	$ 24.5	$ 28.1
Lease liabilities	$ 26.5	$ 30.0
Operating lease, weighted average incremental borrowing rate, percent	4.10%	4.00%
HG/BAM
Lessee, Lease, Description [Line Items]
ROU lease assets	$ 6.2	$ 7.6
Lease liabilities	6.7	8.1
Ark
Lessee, Lease, Description [Line Items]
ROU lease assets	6.6	7.0
Lease liabilities	6.6	7.0
Asset Management (Kudu)
Lessee, Lease, Description [Line Items]
ROU lease assets	5.9	6.4
Lease liabilities	6.8	7.1
Other Operations
Lessee, Lease, Description [Line Items]
ROU lease assets	5.8	7.1
Lease liabilities	$ 6.4	$ 7.8