Loans and Allowance for Loan Losses (Loan Aging Analysis by Portfolio Segment (Including Loans Past Due Over Ninety Days and Non Accrual Loans) and Summary of Non Accrual Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 12,089	$ 17,812
Current	3,082,934	3,008,410
Total loan balances	3,095,023	3,026,222	$ 2,782,439
Loans 90 Days Past Due and Accruing		14
Non-Accrual Loans	8,156	10,530
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,522	9,866
Current	1,064,852	983,000
Total loan balances	1,070,374	992,866	858,369
Non-Accrual Loans	4,096	5,492
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,531	3,271
Current	1,240,866	1,266,262
Total loan balances	1,243,397	1,269,533	1,164,023
Non-Accrual Loans	1,122	1,380
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	965	968
Current	420,143	380,812
Total loan balances	421,108	381,780	373,400
Non-Accrual Loans	420	1,279
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,378	2,990
Current	310,401	324,773
Total loan balances	312,779	327,763	323,378
Non-Accrual Loans	2,130	1,846
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	162	111
Current	25,610	20,513
Total loan balances	25,772	20,624	18,149
Loans 90 Days Past Due and Accruing		14
Non-Accrual Loans	24	15
HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	531	606
Current	21,062	33,050
Total loan balances	21,593	33,656	$ 45,120
Non-Accrual Loans	364	518
30 – 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,901	6,218
30 – 59 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,297	3,300
30 – 59 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	267	1,794
30 – 59 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	548	150
30 – 59 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	681	907
30 – 59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	108	67
60 – 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,859	3,239
60 – 89 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	627	2,046
60 – 89 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,720	369
60 – 89 Days Past Due | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		19
60 – 89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	238	607
60 – 89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	31	15
60 – 89 Days Past Due | HPFC Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	243	183
Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,329	8,355
Greater Than 90 Days | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,598	4,520
Greater Than 90 Days | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	544	1,108
Greater Than 90 Days | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	417	799
Greater Than 90 Days | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,459	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	$ 288	$ 423