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Debt - Summary of Debt Outstanding (Details) € in Millions, $ in Millions	Jun. 30, 2025 USD ($)	Jun. 30, 2025 EUR (€)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Instrument
Total debt	$ 694.6			$ 562.5
Ark 2021 Subordinated Notes
Debt Instrument
Total debt	158.9			154.5
HG Global Senior Notes
Debt Instrument
Total debt	147.6			147.4
Kudu Credit Facility
Debt Instrument
Total debt	246.8			238.6
Bamboo Credit Facility
Debt Instrument
Total debt	104.6			0.0
Other Operations debt
Debt Instrument
Total debt	36.7			22.0
Subordinated Debt \| Ark 2021 Subordinated Notes
Debt Instrument
Unamortized discount and issuance cost	(3.4)			(3.6)
Total debt	$ 158.9			$ 154.5
Effective Rate	10.20%	10.20%		11.80%
Subordinated Debt \| Ark 2021 Subordinated Notes Tranche 1
Debt Instrument
Amount borrowed	$ 45.3	€ 39.1		$ 41.1
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
Senior Notes \| HG Global Senior Notes
Debt Instrument
Amount borrowed	150.0			150.0
Unamortized discount and issuance cost	(2.4)			(2.6)
Total debt	$ 147.6			$ 147.4
Effective Rate	10.90%	10.90%		11.80%
Secured Debt \| Kudu Credit Facility
Debt Instrument
Amount borrowed	$ 253.3			$ 245.3
Unamortized discount and issuance cost	(6.5)			(6.7)
Total debt	$ 253.3		$ 253.3	$ 245.3	$ 210.3	$ 210.3	$ 210.3
Effective Rate	9.30%	9.30%		10.30%
Secured Debt \| Bamboo Credit Facility
Debt Instrument
Amount borrowed	$ 109.7			$ 0.0
Unamortized discount and issuance cost	(5.1)			0.0
Total debt	$ 109.7		$ 110.0	0.0
Effective Rate	10.10%	10.10%
Secured Debt \| Other Operations debt
Debt Instrument
Amount borrowed	$ 37.3			22.4
Unamortized discount and issuance cost	(0.6)			(0.4)
Total debt	$ 36.7			$ 22.0
Effective Rate	8.60%	8.60%		10.20%