Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Balance Sheet Grouping, Financial Statement Captions
Carrying Value	$ 870.4	$ 562.5
Ark 2021 Subordinated Notes
Balance Sheet Grouping, Financial Statement Captions
Fair Value	179.6	173.9
Carrying Value	159.7	154.5
HG Global Senior Notes
Balance Sheet Grouping, Financial Statement Captions
Fair Value	154.0	157.2
Carrying Value	147.7	147.4
Kudu Credit Facility
Balance Sheet Grouping, Financial Statement Captions
Fair Value	289.4	253.3
Carrying Value	274.3	238.6
Bamboo Credit Facility
Balance Sheet Grouping, Financial Statement Captions
Fair Value	106.6	0.0
Carrying Value	104.6	0.0
Distinguished Credit Facility
Balance Sheet Grouping, Financial Statement Captions
Fair Value	139.6	0.0
Carrying Value	138.1	0.0
Distinguished other debt
Balance Sheet Grouping, Financial Statement Captions
Fair Value	10.6	0.0
Carrying Value	10.6	0.0
Other Operations debt
Balance Sheet Grouping, Financial Statement Captions
Fair Value	36.2	23.1
Carrying Value	$ 35.4	$ 22.0