Reserve for Losses and Loss Adjustment Expenses - Schedule of Reserve for Losses and Loss Adjustment Expenses, Net of Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease) [Abstract]
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at beginning of period	$ 1,086,278	$ 1,246,973	$ 1,080,766
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Current year	400,003	441,058	463,530
Prior years - retroactive reinsurance	28,750	37,237	4,991
Prior years - excluding retroactive reinsurance	(1,549)	76,079	31,636
Total incurred losses and loss and adjustment expenses	427,204	554,374	500,157
Deduct: Loss and loss adjustment expense payments net of reinsurance:
Current year	17,842	31,313	32,410
Prior years	395,191	333,277	296,549
Total loss and loss adjustment expense payments	413,033	364,590	328,959
Deduct: Loss reserves ceded in E&S ADC	2,026,110	1,996,913
Reserve for losses and loss adjustment expenses net of reinsurance recoverables at end of period	1,071,699	1,086,278	1,246,973
Add: Reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period	2,027,719	1,998,128	1,359,134
Reserve for losses and loss adjustment expenses gross of reinsurance recoverables on unpaid losses and loss adjustment expenses at end of period	3,099,418	3,084,406	2,606,107
Excess and Surplus Lines
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Prior years - excluding retroactive reinsurance	(5,000)	76,700	32,600
Commercial Auto LPT And E&S ADC | Excess and Surplus Lines
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Prior years - retroactive reinsurance	28,750	37,237	4,991
Prior years - excluding retroactive reinsurance	27,197	51,799	64,403
Deduct: Loss and loss adjustment expense payments net of reinsurance:
Deduct: Change in deferred reinsurance gain - retroactive reinsurance	28,750	37,237	4,991
E&S ADC | Excess and Surplus Lines
Add: Incurred losses and loss adjustment expenses net of reinsurance:
Prior years - excluding retroactive reinsurance	35,045	48,748	0
Deduct: Loss and loss adjustment expense payments net of reinsurance:
Deduct: Loss reserves ceded in E&S ADC	$ 0	$ 313,242	$ 0