Loans and Related Allowance for Credit Losses (Allowance for Loan Losses and Related Investments in Loans Receivable) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	$ 3,058	$ 2,876	$ 2,939	$ 2,723	$ 2,723
Charge-offs	(69)	(123)	(171)	(260)	(292)
Recoveries	17	5	39	55	69
Provision for loan losses	32	149	231	389	439
Allowance for loan losses: Ending balance	3,038	2,907	3,038	2,907	2,939
Ending balance: collectively evaluated for impairment	3,038	2,907	3,038	2,907	2,939
Loans: Ending Balance	418,075	382,616	418,075	382,616	383,904
Ending balance: individually evaluated for impairment	2,938	8,719	2,938	8,719	7,731
Ending balance: collectively evaluated for impairment	413,569	373,355	413,569	373,355	375,645
Commercial, Financial and Agricultural [Member] \| Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	348	402	273	318	318
Charge-offs		(9)		(46)	(46)
Recoveries	3	2	9	2	5
Provision for loan losses	(56)	(33)	13	88	(4)
Allowance for loan losses: Ending balance	295	362	295	362	273
Ending balance: collectively evaluated for impairment	295	362	295	362	273
Loans: Ending Balance	49,722	48,551	49,722	48,551	45,802
Ending balance: individually evaluated for impairment		356		356	468
Ending balance: collectively evaluated for impairment	49,722	48,195	49,722	48,195	45,334
Commercial Loan [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,062	1,125	1,022	948	948
Charge-offs	(9)	(70)	(60)	(70)	(70)
Recoveries			5		2
Provision for loan losses	(3)	100	83	277	142
Allowance for loan losses: Ending balance	1,050	1,155	1,050	1,155	1,022
Ending balance: collectively evaluated for impairment	1,050	1,155	1,050	1,155	1,022
Loans: Ending Balance	135,647	134,340	135,647	134,340	140,369
Ending balance: individually evaluated for impairment	910	5,842	910	5,842	5,031
Ending balance: collectively evaluated for impairment	134,228	128,299	134,228	128,299	135,147
Construction Loan [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	327	172	288	231	231
Provision for loan losses	43	30	82	(29)	57
Allowance for loan losses: Ending balance	370	202	370	202	288
Ending balance: collectively evaluated for impairment	370	202	370	202	288
Loans: Ending Balance	36,950	28,145	36,950	28,145	28,403
Ending balance: collectively evaluated for impairment	36,950	28,145	36,950	28,145	28,403
Mortgage Loan [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,261	1,093	1,285	1,143	1,143
Charge-offs	(48)	(37)	(76)	(120)	(149)
Recoveries	7	1	12	45	45
Provision for loan losses	40	50	39	39	246
Allowance for loan losses: Ending balance	1,260	1,107	1,260	1,107	1,285
Ending balance: collectively evaluated for impairment	1,260	1,107	1,260	1,107	1,285
Loans: Ending Balance	167,198	147,783	167,198	147,783	146,888
Ending balance: individually evaluated for impairment	2,011	2,521	2,011	2,521	2,232
Ending balance: collectively evaluated for impairment	164,128	144,919	164,128	144,919	144,319
Obligations of State and Political Subdivisions [Member] \| Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans: Ending Balance	17,755	13,862	17,755	13,862	13,044
Ending balance: collectively evaluated for impairment	17,755	13,862	17,755	13,862	13,044
Personal Loan [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	60	84	71	83	83
Charge-offs	(12)	(7)	(35)	(24)	(27)
Recoveries	7	2	13	8	17
Provision for loan losses	8	2	14	14	(2)
Allowance for loan losses: Ending balance	63	81	63	81	71
Ending balance: collectively evaluated for impairment	63	81	63	81	71
Loans: Ending Balance	10,803	9,935	10,803	9,935	9,398
Ending balance: individually evaluated for impairment	17		17
Ending balance: collectively evaluated for impairment	10,786	9,935	10,786	9,935	9,398
Acquired with Credit Deterioration [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	1,568	542	1,568	542	528
Acquired with Credit Deterioration [Member] \| Commercial Loan [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans: Ending Balance	509		509		191
Ending balance: individually evaluated for impairment	509	199	509	199	191
Acquired with Credit Deterioration [Member] \| Mortgage Loan [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans: Ending Balance	1,059		1,059		337
Ending balance: individually evaluated for impairment	$ 1,059	$ 343	$ 1,059	$ 343	$ 337

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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

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

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The balance of financing receivables that were collectively evaluated for impairment.

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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 and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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