Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	$ 556.3	$ 575.2
Fair Value | HG Global Senior Notes
Balance Sheet Grouping, Financial Statement Captions
Fair Value	158.8	155.7
Fair Value | Ark 2007 Notes
Balance Sheet Grouping, Financial Statement Captions
Fair Value	29.2	28.4
Fair Value | Ark 2021 Notes
Balance Sheet Grouping, Financial Statement Captions
Fair Value	165.5	163.1
Fair Value | Kudu Credit Facility
Balance Sheet Grouping, Financial Statement Captions
Fair Value	208.2	223.9
Fair Value | Other Operations debt
Balance Sheet Grouping, Financial Statement Captions
Fair Value	35.4	38.2
Carrying Value | HG Global Senior Notes
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	146.6	146.5
Carrying Value | Ark 2007 Notes
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	30.0	30.0
Carrying Value | Ark 2021 Notes
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	154.5	153.7
Carrying Value | Kudu Credit Facility
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	191.6	208.3
Carrying Value | Other Operations debt
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	$ 33.6	$ 36.7