Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$ 564.6	$ 575.2
HG Global Senior Notes
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	158.7	155.7
Carrying Value	146.9	146.5
Ark 2007 Subordinated Notes
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	30.5	28.4
Carrying Value	30.0	30.0
Ark 2021 Subordinated Notes
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	171.8	163.1
Carrying Value	155.5	153.7
Kudu Credit Facility
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	225.6	223.9
Carrying Value	203.8	208.3
Other Operations debt
Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	30.0	38.2
Carrying Value	$ 28.4	$ 36.7