LOANS AND ALLOWANCE FOR LOAN LOSSES (Loan Aging Analysis by Portfolio Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 18,335	$ 17,812
Current	3,081,989	3,008,410
Total Loans Outstanding	3,100,324	3,026,222	$ 2,867,529
Loans 90 Days Past Due and Accruing	14	14
Non-Accrual Loans	11,445	10,530
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,227	9,866
Current	1,028,565	983,000
Total Loans Outstanding	1,035,792	992,866	907,910
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	5,566	5,492
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,743	3,271
Current	1,255,896	1,266,262
Total Loans Outstanding	1,260,639	1,269,533	1,190,052
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	1,590	1,380
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,168	968
Current	426,508	380,812
Total Loans Outstanding	428,676	381,780	386,393
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	785	1,279
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,207	2,990
Current	320,329	324,773
Total Loans Outstanding	323,536	327,763	323,671
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	2,672	1,846
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	438	111
Current	23,227	20,513
Total Loans Outstanding	23,665	20,624	19,506
Loans 90 Days Past Due and Accruing	14	14
Non-Accrual Loans	367	15
HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	552	606
Current	27,464	33,050
Total Loans Outstanding	28,016	33,656	$ 39,997
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	465	518
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,938	6,218
30-59 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,530	3,300
30-59 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,194	1,794
30-59 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,380	150
30-59 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	777	907
30-59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	57	67
30-59 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,880	3,239
60-89 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,396	2,046
60-89 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,126	369
60-89 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	20	19
60-89 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	153	607
60-89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14	15
60-89 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	171	183
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,517	8,355
Greater than 90 Days | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,301	4,520
Greater than 90 Days | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	423	1,108
Greater than 90 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	768	799
Greater than 90 Days | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,277	1,476
Greater than 90 Days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	367	29
Greater than 90 Days | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 381	$ 423