SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	$ 822,490	$ 776,015	$ 742,040
Net Investment Income	34,016	31,126	29,504
Net Losses and Loss Expenses	564,079	520,710	459,764
Amortization of Deferred Policy Acquisition Costs	142,430	128,733	119,072
Other Underwriting Expenses	137,924	129,368	125,863
Net Premiums Written	843,530	804,267	742,140
Deferred Policy Acquisition Costs	73,170	68,028
Liability For Losses and Loss Expenses	1,121,046	1,077,620
Unearned Premiums	577,653	572,958
Other Policy Claims and Benefits Payable	0	0
Commercial Lines [Member]
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	510,153	468,433	412,877
Net Investment Income	0	0	0
Net Losses and Loss Expenses	342,456	321,483	264,053
Amortization of Deferred Policy Acquisition Costs	91,965	84,927	66,253
Other Underwriting Expenses	89,056	85,345	72,245
Net Premiums Written	519,797	501,785	425,986
Deferred Policy Acquisition Costs	43,756	41,225
Liability For Losses and Loss Expenses	859,842	814,681
Unearned Premiums	345,437	347,213
Other Policy Claims and Benefits Payable	0	0
Personal Lines [Member]
Supplementary Insurance Information by Segment [Abstract]
Net Premiums Earned	312,337	307,582	329,163
Net Investment Income	0	0	0
Net Losses and Loss Expenses	221,623	199,227	195,711
Amortization of Deferred Policy Acquisition Costs	50,465	43,806	52,819
Other Underwriting Expenses	48,868	44,023	53,618
Net Premiums Written	323,733	302,482	316,154
Deferred Policy Acquisition Costs	29,414	26,803
Liability For Losses and Loss Expenses	261,204	262,939
Unearned Premiums	232,216	225,745
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	34,016	31,126	29,504
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