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Investments - Schedule of Private Debt and Equity (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2022 project	Dec. 31, 2025 USD ($) note	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Apr. 11, 2025 note
Net Investment Income [Line Items]
Carrying Value		$ 64,152	$ 36,700
Investment Income		1,673	4,133	$ 4,881
Investment Income		3,229	4,855	5,049
Cash distributions from LLCs		4,095	405	43
Proceeds from limited partnership investments redeemed		5,900
Renewable energy LLCs
Net Investment Income [Line Items]
Carrying Value		7,274	7,690
Investment Income		(369)	1,740	2,899
Number of underlying projects sold \| project	2
Proceeds from sale of equity method investments				3,600
Renewable energy notes receivable
Net Investment Income [Line Items]
Carrying Value		0	0
Investment Income		0	138	244
Limited partnerships
Net Investment Income [Line Items]
Carrying Value		13,477	15,108
Investment Income		1,828	2,393	1,566
Private Debt
Net Investment Income [Line Items]
Carrying Value		43,401	13,902
Investment Income		1,770	584	340
Enstar Group Limited
Net Investment Income [Line Items]
Investment Income		498
Commitment to invest in notes receivable		63,500
Excess and Surplus Lines
Net Investment Income [Line Items]
Carrying Value		63,783	36,236
Investment Income		3,229	4,485	4,389
Excess and Surplus Lines \| Sixth Street
Net Investment Income [Line Items]
Number of notes maturing \| note					3
Excess and Surplus Lines \| Notes Receivable One \| Sixth Street
Net Investment Income [Line Items]
Rate of interest					6.79%
Excess and Surplus Lines \| Notes Receivable Two \| Sixth Street
Net Investment Income [Line Items]
Rate of interest					8.04%
Excess and Surplus Lines \| Notes Receivable Three \| Sixth Street
Net Investment Income [Line Items]
Rate of interest					9.04%
Excess and Surplus Lines \| Renewable energy LLCs
Net Investment Income [Line Items]
Carrying Value		7,274	7,690
Investment Income		(369)	1,447	2,375
Proceeds from sale of equity method investments			1,700	3,100
Excess and Surplus Lines \| Renewable energy LLCs \| Investment in LLC
Net Investment Income [Line Items]
Cash distributions from LLCs		$ 48	439
Excess and Surplus Lines \| Renewable energy LLCs \| Minimum \| Investment in LLC \| Various LLCs
Net Investment Income [Line Items]
Ownership percentage		3.60%
Excess and Surplus Lines \| Renewable energy LLCs \| Maximum \| Investment in LLC \| Various LLCs
Net Investment Income [Line Items]
Ownership percentage		5.00%
Excess and Surplus Lines \| Renewable energy notes receivable
Net Investment Income [Line Items]
Carrying Value		$ 0	0
Investment Income		$ 0	61	108
Number of notes issued \| note		2
Rate of interest		12.00%
Total principal balance received			608
Excess and Surplus Lines \| Limited partnerships
Net Investment Income [Line Items]
Carrying Value		$ 13,108	14,644
Investment Income		1,828	2,393	1,566
Outstanding commitments to invest		11,700
Excess and Surplus Lines \| Private Debt
Net Investment Income [Line Items]
Carrying Value		43,401	13,902
Investment Income		$ 1,770	584	340
Excess and Surplus Lines \| Private Speciality Credit
Net Investment Income [Line Items]
Number of notes issued \| note		10
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable One
Net Investment Income [Line Items]
Rate of interest		4.25%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Two
Net Investment Income [Line Items]
Rate of interest		5.25%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Three
Net Investment Income [Line Items]
Rate of interest		6.50%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Four
Net Investment Income [Line Items]
Rate of interest		8.00%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Five
Net Investment Income [Line Items]
Rate of interest		6.00%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Six
Net Investment Income [Line Items]
Rate of interest		7.00%
Excess and Surplus Lines \| Private Speciality Credit \| Notes Receivable Seven
Net Investment Income [Line Items]
Rate of interest		8.00%
Excess and Surplus Lines \| Private Specialty Credit
Net Investment Income [Line Items]
Commitment to invest in notes receivable		$ 80,700
Corporate and Other
Net Investment Income [Line Items]
Carrying Value		369	464
Investment Income		0	370	660
Corporate and Other \| Renewable energy LLCs
Net Investment Income [Line Items]
Carrying Value		0	0
Investment Income		0	293	524
Proceeds from sale of equity method investments			293	524
Corporate and Other \| Renewable energy notes receivable
Net Investment Income [Line Items]
Carrying Value		0	0
Investment Income		$ 0	77	136
Number of notes issued \| note		2
Rate of interest		12.00%
Total principal balance received			761
Corporate and Other \| Limited partnerships
Net Investment Income [Line Items]
Carrying Value		$ 369	464
Investment Income		0	0	0
Corporate and Other \| Private Debt
Net Investment Income [Line Items]
Carrying Value		0	0
Investment Income		$ 0	$ 0	$ 0