Loan Quality and Allowance for Loan Losses (Allowance For Loan Losses, By Loan Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Charge-offs	$ (26)	$ (36)
Recoveries	23	119
Provision	200	120
Loans evaluated for allowance individually	11,798		$ 11,906
Loans evaluated for allowance collectively	930,855		931,794
Total Loans	942,653		943,700
Allowance established for loan evaluated collectively	11,989		11,792
Total Allowance	11,989	11,278	11,792	$ 11,075
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total Loans	204,543		208,805
Residential Real Estate - Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision	36	50
Loans evaluated for allowance individually	466		466
Loans evaluated for allowance collectively	11,025		9,435
Total Loans	11,491		9,901
Allowance established for loan evaluated collectively	260		224
Total Allowance	260	274	224	224
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision	172	17
Loans evaluated for allowance individually	10,878		10,981
Loans evaluated for allowance collectively	422,943		417,447
Total Loans	433,821		428,428
Allowance established for loan evaluated collectively	6,698		6,526
Total Allowance	6,698	6,126	6,526	6,109
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recoveries	8	102
Provision	(45)	(11)
Loans evaluated for allowance collectively	287,680		291,519
Total Loans	287,680		291,519
Allowance established for loan evaluated collectively	2,073		2,110
Total Allowance	2,073	1,984	2,110	1,893
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Charge-offs	(26)	(28)
Recoveries	14	16
Provision	11	11
Loans evaluated for allowance collectively	5,118		5,047
Total Loans	5,118		5,047
Allowance established for loan evaluated collectively	104		105
Total Allowance	104	99	105	100
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision	54	53
Allowance established for loan evaluated collectively	1,491		1,437
Total Allowance	1,491	1,374	1,437	1,321
First Liens [Member] \| Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Charge-offs		(8)
Recoveries	1	1
Provision	(18)	2
Loans evaluated for allowance individually	454		459
Loans evaluated for allowance collectively	155,233		157,975
Total Loans	155,687		158,434
Allowance established for loan evaluated collectively	1,043		1,060
Total Allowance	1,043	1,100	1,060	1,105
Junior Liens & Lines Of Credit [Member] \| Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision	(10)	(2)
Loans evaluated for allowance collectively	48,856		50,371
Total Loans	48,856		50,371
Allowance established for loan evaluated collectively	320		330
Total Allowance	$ 320	$ 321	$ 330	$ 323

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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