LOANS AND ALLOWANCE FOR LOAN LOSSES (Summary of Impaired Loan Balances and Associated Allowance by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	$ 7,282	$ 15,235	$ 9,280
Unpaid Principal Balance - with an allowance recorded	7,282	15,235	9,280
Related Allowance	1,033	1,734	2,009
Average Recorded Investment - with an allowance recorded	8,069	15,075	12,257
Interest Income Recognized - with an allowance recorded	31	26	153
Recorded Investment - without allowance recorded	3,943	4,893	4,310
Unpaid Principal Balance - without allowance recorded	5,859	6,893	6,216
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded	4,123	5,166	4,709
Interest Income Recognized - without allowance recorded	14	15	62
Impaired Financing Receivable, Recorded Investment	11,225	20,128	13,590
Impaired financing receivable, unpaid principal balance	13,141	22,128	15,496
Impaired Financing Receivable, Average Recorded Investment	12,192	20,241	16,966
Impaired Financing Receivable, Interest Income, Accrual Method	45	41	215
Residential Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	3,544	3,048	3,858
Unpaid Principal Balance - with an allowance recorded	3,544	3,048	3,858
Related Allowance	553	485	568
Average Recorded Investment - with an allowance recorded	3,745	3,025	3,177
Interest Income Recognized - with an allowance recorded	30	26	131
Recorded Investment - without allowance recorded	1,515	1,360	1,313
Unpaid Principal Balance - without allowance recorded	1,791	1,740	1,673
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded	1,350	1,292	1,345
Interest Income Recognized - without allowance recorded	7	2	15
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	3,591	11,791	5,422
Unpaid Principal Balance - with an allowance recorded	3,591	11,791	5,422
Related Allowance	368	1,100	1,441
Average Recorded Investment - with an allowance recorded	4,275	11,654	8,900
Interest Income Recognized - with an allowance recorded	1		22
Recorded Investment - without allowance recorded	370	1,400	777
Unpaid Principal Balance - without allowance recorded	677	1,707	1,084
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded	637	1,704	1,132
Interest Income Recognized - without allowance recorded	3	10	29
Commercial
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	0	1	0
Unpaid Principal Balance - with an allowance recorded	0	1	0
Related Allowance	0	0	0
Average Recorded Investment - with an allowance recorded			31
Recorded Investment - without allowance recorded	1,714	1,993	1,791
Unpaid Principal Balance - without allowance recorded	2,923	3,167	2,964
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded	1,740	2,024	1,920
Interest Income Recognized - without allowance recorded	2	3	10
Home Equity
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	147	297	0
Unpaid Principal Balance - with an allowance recorded	147	297	0
Related Allowance	112	83	0
Average Recorded Investment - with an allowance recorded	49	298	125
Recorded Investment - without allowance recorded	344	133	429
Unpaid Principal Balance - without allowance recorded	468	269	495
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded	396	139	310
Interest Income Recognized - without allowance recorded	2		8
Consumer
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	0	0	0
Unpaid Principal Balance - with an allowance recorded	0	0	0
Related Allowance	0	0	0
Average Recorded Investment - with an allowance recorded			0
Recorded Investment - without allowance recorded	0	7	0
Unpaid Principal Balance - without allowance recorded	0	10	0
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average Recorded Investment - without allowance recorded		7	2
HPFC Portfolio Segment
Financing Receivable, Impaired [Line Items]
Recorded Investment - with an allowance recorded	0	98	0
Unpaid Principal Balance - with an allowance recorded	0	98	0
Related Allowance	0	66	0
Average Recorded Investment - with an allowance recorded		98	24
Recorded Investment - without allowance recorded	0	0	0
Unpaid Principal Balance - without allowance recorded	0	0	0
Impaired Financing Receivable With No Related Allowance Related Allowance	$ 0	$ 0
Average Recorded Investment - without allowance recorded			$ 0

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