INVESTMENTS (Summary of Amortized Cost and Fair Value of Debt and Equity Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	$ 432,051	$ 422,300
Debt securities - available-for-sale, at fair value:	424,148	423,238
Held-to-maturity securities, Amortized Cost or Cost	5,255	5,349
Total investments, Amortized Cost or Cost	437,306	441,734
Total investments, Gross Unrealized Gain	299	4,597
Total investments, Gross Unrealized Loss	8,379	2,385
Total investments, Fair Value	429,226	443,946
Debt Securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	432,051	422,300
Debt securities, available-for-sale securities, Gross Unrealized Gain	295	2,938
Debt securities, available-for-sale securities, Gross Unrealized Losses	8,198	2,000
Debt securities - available-for-sale, at fair value:	424,148	423,238
Held-to-maturity securities, Amortized Cost or Cost	5,255	5,349
Held-to-maturity securities, Gross Unrealized Gains	4	31
Held-to-maturity securities, Gross Unrealized Losses	181	106
Held-to-maturity securities, fair value	5,078	5,274
United States Government Obligations and Authorities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	116,969	98,739
Debt securities, available-for-sale securities, Gross Unrealized Gain	20	244
Debt securities, available-for-sale securities, Gross Unrealized Losses	2,752	846
Debt securities - available-for-sale, at fair value:	114,237	98,137
Held-to-maturity securities, Amortized Cost or Cost	4,140	4,160
Held-to-maturity securities, Gross Unrealized Gains	1	9
Held-to-maturity securities, Gross Unrealized Losses	174	106
Held-to-maturity securities, fair value	3,967	4,063
Obligations of States and Political Subdivisions
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	9,891	66,319
Debt securities, available-for-sale securities, Gross Unrealized Gain	9	325
Debt securities, available-for-sale securities, Gross Unrealized Losses	221	378
Debt securities - available-for-sale, at fair value:	9,679	66,266
Corporate
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	287,901	239,435
Debt securities, available-for-sale securities, Gross Unrealized Gain	246	2,233
Debt securities, available-for-sale securities, Gross Unrealized Losses	4,934	749
Debt securities - available-for-sale, at fair value:	283,213	240,919
Held-to-maturity securities, Amortized Cost or Cost	1,035	1,123
Held-to-maturity securities, Gross Unrealized Gains	3	21
Held-to-maturity securities, Gross Unrealized Losses	6	0
Held-to-maturity securities, fair value	1,032	1,144
International
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost	17,290	17,807
Debt securities, available-for-sale securities, Gross Unrealized Gain	20	136
Debt securities, available-for-sale securities, Gross Unrealized Losses	291	27
Debt securities - available-for-sale, at fair value:	17,019	17,916
Held-to-maturity securities, Amortized Cost or Cost	80	66
Held-to-maturity securities, Gross Unrealized Gains	0	1
Held-to-maturity securities, Gross Unrealized Losses	1	0
Held-to-maturity securities, fair value	$ 79	67
Equity Securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, at amortized cost		14,085
Debt securities, available-for-sale securities, Gross Unrealized Gain		1,628
Debt securities, available-for-sale securities, Gross Unrealized Losses		279
Debt securities - available-for-sale, at fair value:		$ 15,434