Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 34.0	$ 22.6
Lease liability	$ 34.2	$ 22.8
Operating lease, weighted average incremental borrowing rate, percent	4.80%	4.60%
HG/BAM
Lessee, Lease, Description [Line Items]
ROU lease asset	$ 9.8	$ 10.4
Lease liability	9.8	10.4
NSM Holding Co LLC
Lessee, Lease, Description [Line Items]
ROU lease asset	16.8	4.8
Lease liability	16.8	4.8
Kudu investments
Lessee, Lease, Description [Line Items]
ROU lease asset	2.2	2.3
Lease liability	2.2	2.3
Other
Lessee, Lease, Description [Line Items]
ROU lease asset	5.2	5.1
Lease liability	$ 5.4	$ 5.3