FAIR VALUE (Financial Instruments Measured at Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Debt securities	$ 378,879	$ 339,178
Equity securities	41,334	38,534
Total investments	420,213	377,712
United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	65,810	61,553
Total investments	65,810	61,553
Obligations of States and Political Subdivisions [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	150,873	110,702
Total investments	150,873	110,702
Corporate [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	149,210	154,620
Total investments	149,210	154,620
International [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	12,986	12,303
Total investments	12,986	12,303
Level 1 [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	38,933	34,733
Equity securities	40,458	38,012
Total investments	79,391	72,745
Level 1 [Member] | United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	38,933	34,733
Level 2 [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	339,946	304,445
Equity securities	876	522
Total investments	340,822	304,967
Level 2 [Member] | United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	26,877	26,820
Level 2 [Member] | Obligations of States and Political Subdivisions [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	150,873	110,702
Level 2 [Member] | Corporate [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	149,210	154,620
Level 2 [Member] | International [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities	$ 12,986	$ 12,303