Liabilities for Losses and Loss Expenses (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Claims and Claims Adjustment Expense [Abstract]
Balance at January 1	$ 1,126,156,838	$ 1,121,046,000
Less reinsurance recoverable	(437,014,000)	(451,184,000)
Cumulative effect of adoption of updated accounting guidance for credit losses at January 1	0	1,132,000
Net balance at January 1	689,143,000	670,994,000
Incurred related to [Abstract]
Current year	159,289,000	146,413,000
Prior years	(8,393,000)	(8,307,000)
Total incurred	150,896,000	138,106,000
Paid related to [Abstract]
Current year	47,886,000	41,205,000
Prior years	98,197,000	98,820,000
Total paid	146,083,000	140,025,000
Net balance at end of period	693,956,000	669,075,000
Plus reinsurance recoverable	430,496,000	454,460,000
Balance at end of period	$ 1,124,452,191	$ 1,123,535,000
Percentage of development	1.20%	1.20%