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Debt - Ark Subordinated Notes (Details) € in Millions				1 Months Ended		3 Months Ended	6 Months Ended
Debt - Ark Subordinated Notes (Details) € in Millions	Jul. 21, 2025	Sep. 08, 2021 USD ($)	Aug. 11, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jul. 31, 2021	Sep. 30, 2021 USD ($) transaction	Jun. 30, 2026 USD ($)	Jun. 30, 2026 EUR (€)	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Jul. 13, 2021 USD ($)	Jul. 13, 2021 EUR (€)	Mar. 23, 2021 USD ($)
Ark 2021 Subordinated Notes \| Subordinated Debt
Debt Instrument
Face value				$ 163,300,000		$ 163,300,000
Number of transactions \| transaction						3
Proceeds from debt, net of debt issuance costs						$ 157,800,000
Ark 2021 Subordinated Notes Tranche 1 \| Subordinated Debt
Debt Instrument
Face value														$ 46,300,000	€ 39.1
Amount borrowed							$ 44,900,000	€ 39.1		$ 45,800,000
Ark 2021 Subordinated Notes Tranche 1 \| Subordinated Debt \| Euro Interbank Offered Rate (EURIBOR)
Debt Instrument
Basis spread on variable rate					5.75%
Ark 2021 Subordinated Notes Tranche 2 \| Subordinated Debt
Debt Instrument
Face value			$ 47,000,000.0
Amount borrowed							47,000,000.0			47,000,000.0
Ark 2021 Subordinated Notes Tranche 2 \| Subordinated Debt \| London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate			5.75%
Kudu Credit Facility \| Secured Debt
Debt Instrument
Face value																$ 500,000,000.0
Basis spread on variable rate	3.10%
Amount borrowed							$ 358,300,000		$ 358,300,000	358,300,000	$ 253,300,000	$ 253,300,000	$ 245,300,000
Kudu Credit Facility \| Secured Debt \| Secured Overnight Financing Rate (SOFR)
Debt Instrument
Basis spread on variable rate		0.26%	0.26%
Ark 2021 Subordinated Notes Tranche 3 \| Subordinated Debt
Debt Instrument
Face value		$ 70,000,000.0
Debt instrument, period for interest rate increase		10 years
Additional interest rate							1.00%
Solvency capital requirement				120.00%
Debt to capital requirement				40.00%
Amount borrowed							$ 70,000,000.0			$ 70,000,000.0
Ark 2021 Subordinated Notes Tranche 3 \| Subordinated Debt \| London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate		6.10%