Reserves for Losses and Loss Settlement Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross liability for losses and loss settlement expenses at beginning of year		$ 1,638,755	$ 1,497,274
Ceded losses and loss settlement expenses		(191,640)	(146,875)
Net liability for losses and loss settlement expenses at beginning of year		1,447,115	1,350,399
Losses and loss settlement expenses incurred for claims occurring during
Current year		568,480	701,664
Prior years	$ (3,200)	(361)	67,750
Total incurred		568,119	769,414
Losses and loss settlement expense payments for claims occurring during
Current year		113,707	191,899
Prior years		314,090	480,800
Total paid		427,797	672,699
Net liability for losses and loss settlement expenses at end of period	1,587,437	1,587,437	1,447,115
Ceded losses and loss settlement expenses	207,504	207,504	191,640
Gross liability for losses and loss settlement expenses at end of period	$ 1,794,941	$ 1,794,941	$ 1,638,755