LOANS AND ALLOWANCE FOR LOAN LOSSES (Loan Aging Analysis by Portfolio Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 27,054	$ 25,465
Current	2,618,085	2,569,099
Total Loans Outstanding	2,645,139	2,594,564	$ 2,492,634
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	21,523	20,713
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,918	5,611
Current	813,721	796,883
Total Loans Outstanding	819,639	802,494	811,974
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	4,105	3,945
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	15,173	13,703
Current	1,081,302	1,037,077
Total Loans Outstanding	1,096,475	1,050,780	952,481
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	12,858	12,849
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,734	2,526
Current	331,873	331,113
Total Loans Outstanding	333,607	333,639	292,064
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	1,994	2,088
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,404	2,347
Current	320,422	327,560
Total Loans Outstanding	322,826	329,907	344,497
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	1,548	1,620
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	34	42
Current	16,635	17,290
Total Loans Outstanding	16,669	17,332	17,189
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	4	4
HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,791	1,236
Current	54,132	59,176
Total Loans Outstanding	55,923	60,412	$ 74,429
Loans 90 Days Past Due and Accruing	0	0
Non-Accrual Loans	1,014	207
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,601	4,639
30-59 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,188	1,783
30-59 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,393	855
30-59 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	76	633
30-59 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	870	892
30-59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	18	38
30-59 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,056	438
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,032	2,187
60-89 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	354	924
60-89 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	127	223
60-89 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	92	218
60-89 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	188	134
60-89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12	0
60-89 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	259	688
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,421	18,639
Greater than 90 Days | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,376	2,904
Greater than 90 Days | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,653	12,625
Greater than 90 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,566	1,675
Greater than 90 Days | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,346	1,321
Greater than 90 Days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	4
Greater than 90 Days | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 476	$ 110