Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
ROU lease asset	$ 42.2	$ 37.6
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Lease liability	$ 45.2	$ 38.3
Weighted Average Incremental Borrowing Rate	5.00%	4.60%
HG/BAM
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 7.6	$ 10.1
Lease liability	8.1	10.1
NSM
Lessee, Lease, Description [Line Items]
ROU lease asset	14.0	17.1
Lease liability	15.2	17.1
Kudu
Lessee, Lease, Description [Line Items]
ROU lease asset	6.5	2.0
Lease liability	7.1	2.0
Other
Lessee, Lease, Description [Line Items]
ROU lease asset	7.1	8.4
Lease liability	7.8	$ 9.1
Ark
Lessee, Lease, Description [Line Items]
ROU lease asset	7.0
Lease liability	$ 7.0