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Debt - Summary of Debt Outstanding (Details) € in Millions, $ in Millions	Mar. 31, 2026 USD ($)	Mar. 31, 2026 EUR (€)	Dec. 31, 2025 USD ($)	Jul. 21, 2025 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
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Total debt	$ 834.8		$ 837.0
Ark 2021 Subordinated Notes
Debt Instrument
Total debt	159.3		159.7
Kudu Credit Facility
Debt Instrument
Total debt	350.6		350.4
HG Global Senior Notes
Debt Instrument
Total debt	147.9		147.8
Distinguished Credit Facility
Debt Instrument
Total debt	129.6		129.9
Distinguished other debt, carrying value
Debt Instrument
Total debt	11.2		10.9
Other Operations debt
Debt Instrument
Total debt	$ 36.2		$ 38.3
Subordinated Debt \| Ark
Debt Instrument
Effective yield (as a percent)	9.70%	9.70%	10.20%
Subordinated Debt \| Ark 2021 Subordinated Notes
Debt Instrument
Unamortized issuance cost	$ (3.0)		$ (3.1)
Total debt	159.3		159.7
Subordinated Debt \| Ark 2021 Subordinated Notes Tranche 1
Debt Instrument
Amount borrowed	45.3	€ 39.1	45.8
Subordinated Debt \| Ark 2021 Subordinated Notes Tranche 2
Debt Instrument
Amount borrowed	47.0		47.0
Subordinated Debt \| Ark 2021 Subordinated Notes Tranche 3
Debt Instrument
Amount borrowed	70.0		70.0
Secured Debt \| Kudu Credit Facility
Debt Instrument
Amount borrowed	358.3		358.3		$ 253.3	$ 245.3
Unamortized discount and issuance cost	(7.7)		(7.9)
Total debt	$ 350.6		$ 350.4	$ 253.3
Effective yield (as a percent)	8.00%	8.00%	8.90%
Secured Debt \| Total Distinguished debt
Debt Instrument
Total debt	$ 140.8		$ 140.8
Secured Debt \| Distinguished Credit Facility
Debt Instrument
Amount borrowed	131.1		131.4
Unamortized discount and issuance cost	(1.5)		(1.5)
Total debt	$ 129.6		$ 129.9
Effective yield (as a percent)	9.90%	9.90%	10.30%
Secured Debt \| Distinguished other debt, carrying value
Debt Instrument
Total debt	$ 11.2		$ 10.9
Effective yield (as a percent)	10.80%	10.80%	10.90%
Secured Debt \| Other Operations debt
Debt Instrument
Amount borrowed	$ 36.8		$ 38.7
Unamortized discount and issuance cost	(0.6)		(0.4)
Total debt	$ 36.2		$ 38.3
Effective yield (as a percent)	8.60%	8.60%	8.30%
Senior Notes \| HG Global Senior Notes
Debt Instrument
Amount borrowed	$ 150.0		$ 150.0
Unamortized discount and issuance cost	(2.1)		(2.2)
Total debt	$ 147.9		$ 147.8
Effective yield (as a percent)	10.30%	10.30%	10.80%