SEGMENT INFORMATION (Net Premiums) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	$ 754,846	$ 694,994	$ 586,783
Property and Casualty Insurance Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Reinsurance assumed	18,485	16,889	14,869
Other	2,635	1,919	1,651
Property and Casualty Insurance Segment [Member] | Fire and Allied Lines [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums earned	208,030	173,249	153,839
Property and Casualty Insurance Segment [Member] | Other Liability [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums earned	199,548	197,842	159,977
Property and Casualty Insurance Segment [Member] | Automobile [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums earned	169,211	155,572	133,974
Property and Casualty Insurance Segment [Member] | Workers' Compensation [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums earned	81,616	68,643	54,404
Property and Casualty Insurance Segment [Member] | Fidelity and Surety [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums earned	18,746	17,713	16,665
Property and Casualty Insurance Segment [Member] | Operating Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	694,192	629,411	533,771
Property and Casualty Insurance Segment [Member] | Reinsurance Assumed Line of Business [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Reinsurance assumed	14,406	14,473	13,261
Life Insurance Segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Other	261	274	262
Life Insurance Segment [Member] | Ordinary Life (Excluding Universal Life) [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	38,875	44,468	30,374
Life Insurance Segment [Member] | Universal Life Policy Fees [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	11,871	11,768	10,995
Life Insurance Segment [Member] | Accident and Health [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	1,302	1,363	1,472
Life Insurance Segment [Member] | Immediate Annuities with Life Contingencies [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	8,837	8,158	10,276
Life Insurance Segment [Member] | Operating Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net premium earned	$ 61,146	$ 66,031	$ 53,379