LOANS AND ALLOWANCE FOR LOAN LOSSES (Loan Aging Analysis by Portfolio Segment) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) loan	Mar. 31, 2018 USD ($) loan	Dec. 31, 2018 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of TDRs | loan	0	0
Total Past Due	$ 16,562		$ 17,812
Current	3,025,880		3,008,410
Total Loans Outstanding	3,042,442	$ 2,789,148	3,026,222
Loans 90 Days Past Due and Accruing	14		14
Non-Accrual Loans	10,153		10,530
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,895		9,866
Current	1,010,547		983,000
Total Loans Outstanding	1,017,442	860,533	992,866
Loans 90 Days Past Due and Accruing	0		0
Non-Accrual Loans	5,415		5,492
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,669		3,271
Current	1,254,805		1,266,262
Total Loans Outstanding	1,258,474	1,169,533	1,269,533
Loans 90 Days Past Due and Accruing	0		0
Non-Accrual Loans	975		1,380
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,990		968
Current	388,992		380,812
Total Loans Outstanding	390,982	378,015	381,780
Loans 90 Days Past Due and Accruing	0		0
Non-Accrual Loans	802		1,279
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,997		2,990
Current	320,972		324,773
Total Loans Outstanding	323,969	320,642	327,763
Loans 90 Days Past Due and Accruing	0		0
Non-Accrual Loans	2,467		1,846
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	428		111
Current	20,305		20,513
Total Loans Outstanding	20,733	18,011	20,624
Loans 90 Days Past Due and Accruing	14		14
Non-Accrual Loans	9		15
HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	583		606
Current	30,259		33,050
Total Loans Outstanding	30,842	$ 42,414	33,656
Loans 90 Days Past Due and Accruing	0		0
Non-Accrual Loans	485		518
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,783		6,218
30-59 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,135		3,300
30-59 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,387		1,794
30-59 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,196		150
30-59 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,017		907
30-59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43		67
30-59 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5		0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,582		3,239
60-89 Days Past Due | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	491		2,046
60-89 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,885		369
60-89 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	470		19
60-89 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	192		607
60-89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	362		15
60-89 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	182		183
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,197		8,355
Greater than 90 Days | Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,269		4,520
Greater than 90 Days | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	397		1,108
Greater than 90 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	324		799
Greater than 90 Days | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,788		1,476
Greater than 90 Days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	23		29
Greater than 90 Days | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 396		$ 423