Loans and Allowance for Loan Losses, Allowance for Loan Losses by Portfolio Segment (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
Allowance for Loan Losses [Roll Forward]
Beginning balance			$ 5,094	$ 4,525	$ 4,525
Charge-offs			(521)	(659)	(691)
Recoveries			134	167	740
Provision (recovery)	$ 195	$ 110	507	395	520
Ending balance	5,214	4,428	5,214	4,428	5,094
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	540		540		912
Ending balances collectively evaluated for impairment	4,674		4,674		4,182
Loans receivable, individually evaluated for impairment	8,103		8,103		10,862
Loans receivable, collectively evaluated for impairment	524,913		524,913		491,937
Total financing receivables	533,016		533,016		502,799
Commercial and Industrial [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			518	561	561
Charge-offs			(99)	(15)	(19)
Recoveries			31	154	154
Provision (recovery)			72	(270)	(178)
Ending balance	522	430	522	430	518
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	185		185		247
Ending balances collectively evaluated for impairment	337		337		271
Loans receivable, individually evaluated for impairment	540		540		758
Loans receivable, collectively evaluated for impairment	27,812		27,812		23,655
Total financing receivables	28,352		28,352		24,413
Commercial Real Estate [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			1,609	1,569	1,569
Charge-offs			0	(476)	(476)
Recoveries			50	4	575
Provision (recovery)			158	400	(59)
Ending balance	1,817	1,497	1,817	1,497	1,609
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	282		282		257
Ending balances collectively evaluated for impairment	1,535		1,535		1,352
Loans receivable, individually evaluated for impairment	3,583		3,583		3,631
Loans receivable, collectively evaluated for impairment	180,949		180,949		173,196
Total financing receivables	184,532		184,532		176,827
Construction and Land [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			879	661	661
Charge-offs			(312)	0	0
Recoveries			0	0	0
Provision (recovery)			9	165	218
Ending balance	576	826	576	826	879
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	0		0		357
Ending balances collectively evaluated for impairment	576		576		522
Loans receivable, individually evaluated for impairment	2,694		2,694		5,234
Loans receivable, collectively evaluated for impairment	61,584		61,584		48,928
Total financing receivables	64,278		64,278		54,162
Consumer [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			105	21	21
Charge-offs			(9)	(97)	(114)
Recoveries			4	2	2
Provision (recovery)			23	152	196
Ending balance	123	78	123	78	105
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	0		0		0
Ending balances collectively evaluated for impairment	123		123		105
Loans receivable, individually evaluated for impairment	0		0		0
Loans receivable, collectively evaluated for impairment	5,144		5,144		5,068
Total financing receivables	5,144		5,144		5,068
Student [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			72	76	76
Charge-offs			(21)	(20)	(31)
Recoveries			0	0	0
Provision (recovery)			23	11	27
Ending balance	74	67	74	67	72
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	0		0		0
Ending balances collectively evaluated for impairment	74		74		72
Loans receivable, individually evaluated for impairment	0		0		0
Loans receivable, collectively evaluated for impairment	9,448		9,448		10,677
Total financing receivables	9,448		9,448		10,677
Residential Real Estate [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			1,174	943	943
Charge-offs			0	(51)	(51)
Recoveries			48	4	6
Provision (recovery)			114	100	276
Ending balance	1,336	996	1,336	996	1,174
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	0		0		0
Ending balances collectively evaluated for impairment	1,336		1,336		1,174
Loans receivable, individually evaluated for impairment	713		713		581
Loans receivable, collectively evaluated for impairment	198,436		198,436		186,523
Total financing receivables	199,149		199,149		187,104
Home Equity Lines of Credit [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			387	307	307
Charge-offs			(80)	0	0
Recoveries			1	3	3
Provision (recovery)			108	72	77
Ending balance	416	382	416	382	387
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	73		73		51
Ending balances collectively evaluated for impairment	343		343		336
Loans receivable, individually evaluated for impairment	573		573		658
Loans receivable, collectively evaluated for impairment	41,540		41,540		43,890
Total financing receivables	42,113		42,113		44,548
Unallocated [Member]
Allowance for Loan Losses [Roll Forward]
Beginning balance			350	387	387
Charge-offs			0	0	0
Recoveries			0	0	0
Provision (recovery)			0	(235)	(37)
Ending balance	350	$ 152	350	$ 152	350
Additional Information on Allowance for Loan Losses and Recorded Investment in Loans Receivable [Abstract]
Ending balances individually evaluated for impairment	0		0		0
Ending balances collectively evaluated for impairment	350		350		350
Loans receivable, individually evaluated for impairment	0		0		0
Loans receivable, collectively evaluated for impairment	0		0		0
Total financing receivables	$ 0		$ 0		$ 0

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

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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

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

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