SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	$ 882,071	$ 822,490	$ 776,015
Net Investment Income	40,853	34,016	31,126
Net Losses and Loss Expenses	609,178	564,079	520,710
Amortization of Deferred Policy Acquisition Costs	154,214	142,430	128,733
Other Underwriting Expenses	151,748	137,924	129,368
Net Premiums Written	895,697	843,530	804,267
Deferred Policy Acquisition Costs	75,043	73,170
Liability For Losses and Loss Expenses	1,126,157	1,121,046
Unearned Premiums	599,411	577,653
Other Policy Claims and Benefits Payable	0	0
Commercial Lines [Member]
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	533,029	521,227	478,966
Net Investment Income	0	0	0
Net Losses and Loss Expenses	345,401	342,456	321,483
Amortization of Deferred Policy Acquisition Costs	94,842	91,965	84,927
Other Underwriting Expenses	93,325	89,056	85,345
Net Premiums Written	528,429	530,846	512,674
Deferred Policy Acquisition Costs	42,775	43,756
Liability For Losses and Loss Expenses	869,393	859,842
Unearned Premiums	341,664	345,437
Other Policy Claims and Benefits Payable	0	0
Personal Lines [Member]
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	349,042	301,263	297,049
Net Investment Income	0	0	0
Net Losses and Loss Expenses	263,777	221,623	199,227
Amortization of Deferred Policy Acquisition Costs	59,372	50,465	43,806
Other Underwriting Expenses	58,423	48,868	44,023
Net Premiums Written	367,268	312,684	291,593
Deferred Policy Acquisition Costs	32,268	29,414
Liability For Losses and Loss Expenses	256,764	261,204
Unearned Premiums	257,747	232,216
Other Policy Claims and Benefits Payable	0	0
Investments [Member]
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	0	0	0
Net Investment Income	40,853	34,016	31,126
Net Losses and Loss Expenses	0	0	0
Amortization of Deferred Policy Acquisition Costs	0	0	0
Other Underwriting Expenses	0	0	0
Net Premiums Written	0	0	$ 0
Deferred Policy Acquisition Costs	0	0
Liability For Losses and Loss Expenses	0	0
Unearned Premiums	0	0
Other Policy Claims and Benefits Payable	$ 0	$ 0