FAIR VALUE (Financial Instruments Measured at Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	$ 383,910	$ 374,756
Equity securities, available-for-sale	45,445	29,375
Total investments	429,355	404,131
United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	85,622	62,205
Total investments	85,621	62,205
Obligations of States and Political Subdivisions [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	86,919	151,183
Total investments	86,919	151,183
Corporate [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	196,733	149,505
Total investments	196,733	149,505
International [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	14,636	11,863
Total investments	14,637	11,863
Level 1 [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	49,028	36,560
Equity securities, available-for-sale	45,445	28,960
Total investments	94,473	65,520
Level 1 [Member] | United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	49,028	36,560
Level 2 [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	334,882	338,196
Equity securities, available-for-sale		415
Total investments	334,882	338,611
Level 2 [Member] | United States Government Obligations and Authorities [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	36,594	25,645
Level 2 [Member] | Obligations of States and Political Subdivisions [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	86,919	151,183
Level 2 [Member] | Corporate [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	196,733	149,505
Level 2 [Member] | International [Member]
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale	$ 14,636	$ 11,863