Loans and Allowance for Loan Losses (Summary of Impaired Loan Balances and Associated Allowance by Portfolio Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded	$ 9,280	$ 14,858	$ 5,475
Unpaid principal balance with related allowance recorded	9,280	14,858	5,507
Average recorded investment with related allowance recorded	12,257	9,418	9,857
Interest income recognized with related allowance recorded	153	106	114
Recorded investment without related allowance recorded	4,310	5,396	9,760
Unpaid principal balance without related allowance recorded	6,216	7,756	12,942
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	4,709	6,970	6,695
Interest income recognized without related allowance recorded	62	76	90
Recorded investment, total impaired loans	13,590	20,254	15,235
Unpaid principal balance, total impaired loans	15,496	22,614	18,449
Related allowance, total impaired loans	2,009	2,007	1,369
Average recorded investment, total impaired loans	16,966	16,388	16,552
Interest income recognized, total impaired loans	215	182	204
Residential real estate loans
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded	3,858	3,019	3,191
Unpaid principal balance with related allowance recorded	3,858	3,019	3,191
Average recorded investment with related allowance recorded	3,177	3,088	6,064
Interest income recognized with related allowance recorded	131	106	112
Recorded investment without related allowance recorded	1,313	1,329	2,835
Unpaid principal balance without related allowance recorded	1,673	1,800	4,353
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	1,345	2,057	2,175
Interest income recognized without related allowance recorded	15	9	8
Related allowance, total impaired loans	568	483	544
Commercial real estate loans
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded	5,422	11,443	1,825
Unpaid principal balance with related allowance recorded	5,422	11,443	1,857
Average recorded investment with related allowance recorded	8,900	5,165	1,753
Interest income recognized with related allowance recorded	22
Recorded investment without related allowance recorded	777	1,874	2,785
Unpaid principal balance without related allowance recorded	1,084	2,369	3,426
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	1,132	2,214	2,719
Interest income recognized without related allowance recorded	29	51	65
Related allowance, total impaired loans	1,441	1,373	644
Commercial loans
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded			156
Unpaid principal balance with related allowance recorded			156
Average recorded investment with related allowance recorded	31	762	945
Interest income recognized with related allowance recorded			2
Recorded investment without related allowance recorded	1,791	2,028	3,781
Unpaid principal balance without related allowance recorded	2,964	3,209	4,325
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	1,920	2,507	1,412
Interest income recognized without related allowance recorded	10	16	17
Related allowance, total impaired loans	0	0	92
Home equity loans
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded		299	303
Unpaid principal balance with related allowance recorded		299	303
Average recorded investment with related allowance recorded	125	305	900
Recorded investment without related allowance recorded	429	158	285
Unpaid principal balance without related allowance recorded	495	368	688
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	310	180	369
Interest income recognized without related allowance recorded	8
Related allowance, total impaired loans	0	86	89
Consumer loans
Financing Receivable, Impaired [Line Items]
Average recorded investment with related allowance recorded			195
Recorded investment without related allowance recorded		7	74
Unpaid principal balance without related allowance recorded		10	150
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded	2	12	$ 20
Related allowance, total impaired loans	0	0
HPFC Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance recorded		97
Unpaid principal balance with related allowance recorded		97
Average recorded investment with related allowance recorded	24	98
Impaired Financing Receivable With No Related Allowance Related Allowance	0	0
Average recorded investment without related allowance recorded
Related allowance, total impaired loans	$ 0	$ 65

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