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

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 17,812	$ 22,945
Current	3,008,410	2,759,494
Total loan balances	3,026,222	2,782,439	$ 2,594,564
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	14
Non-Accrual Loans	10,530	15,314
Residential real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,866	9,477
Current	983,000	848,892
Total loan balances	992,866	858,369	802,494
Non-Accrual Loans	5,492	4,979
Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,271	6,700
Current	1,266,262	1,157,323
Total loan balances	1,269,533	1,164,023	1,050,780
Non-Accrual Loans	1,380	5,642
Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	968	2,223
Current	380,812	371,177
Total loan balances	381,780	373,400	333,639
Non-Accrual Loans	1,279	2,000
Home equity loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,990	2,548
Current	324,773	320,830
Total loan balances	327,763	323,378	329,907
Non-Accrual Loans	1,846	1,650
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	111	67
Current	20,513	18,082
Total loan balances	20,624	18,149	17,332
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	14
Non-Accrual Loans	15
HPFC Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	606	1,930
Current	33,050	43,190
Total loan balances	33,656	45,120	$ 60,412
Non-Accrual Loans	518	1,043
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,218	6,291
Financing Receivables, 30 to 59 Days Past Due [Member] \| Residential real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,300	3,871
Financing Receivables, 30 to 59 Days Past Due [Member] \| Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,794	849
Financing Receivables, 30 to 59 Days Past Due [Member] \| Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	150	329
Financing Receivables, 30 to 59 Days Past Due [Member] \| Home equity loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	907	1,046
Financing Receivables, 30 to 59 Days Past Due [Member] \| Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	67	57
Financing Receivables, 30 to 59 Days Past Due [Member] \| HPFC Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		139
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,239	3,822
Financing Receivables, 60 to 89 Days Past Due [Member] \| Residential real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,046	1,585
Financing Receivables, 60 to 89 Days Past Due [Member] \| Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	369	323
Financing Receivables, 60 to 89 Days Past Due [Member] \| Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19	359
Financing Receivables, 60 to 89 Days Past Due [Member] \| Home equity loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	607	173
Financing Receivables, 60 to 89 Days Past Due [Member] \| Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	15	10
Financing Receivables, 60 to 89 Days Past Due [Member] \| HPFC Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	183	1,372
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,355	12,832
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Residential real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,520	4,021
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,108	5,528
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	799	1,535
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Home equity loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,476	1,329
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	29
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| HPFC Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 423	$ 419