Allowance for Loan Losses - Allowance by Impairment Methodology and Loans by Impairment Methodology (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Allowance for loan losses:
Beginning Balance		$ 6,718	$ 10,644	$ 10,644
Charge-offs		(1,420)	(847)	(927)
Recoveries		377	619	851
Provision for (recovery of) loan losses	$ (100)	(100)	(700)	(3,850)
Ending Balance	9,716	5,575	9,716	6,718
Ending Balance:
Allowance for loan losses, Individually evaluated for impairment	1,709	750	1,709	1,907
Allowance for loan losses, Collectively evaluated for impairment	8,007	4,825	8,007	4,811
Loans:
Ending Balance	374,690	406,413	374,690	378,410
Loans, Individually evaluated for impairment	16,843	8,840	16,843	13,922
Loans, Collectively evaluated for impairment	357,847	397,573	357,847	364,488
Construction and Land Development [Member]
Allowance for loan losses:
Beginning Balance		1,403	2,710	2,710
Charge-offs			(91)	(91)
Recoveries		3	79	80
Provision for (recovery of) loan losses		(150)	(832)	(1,296)
Ending Balance	1,866	1,256	1,866	1,403
Ending Balance:
Allowance for loan losses, Individually evaluated for impairment	626	132	626	245
Allowance for loan losses, Collectively evaluated for impairment	1,240	1,124	1,240	1,158
Loans:
Ending Balance	29,862	29,935	29,862	29,475
Loans, Individually evaluated for impairment	3,382	3,081	3,382	3,205
Loans, Collectively evaluated for impairment	26,480	26,854	26,480	26,270
Secured by 1-4 Family Residential [Member]
Allowance for loan losses:
Beginning Balance		1,204	2,975	2,975
Charge-offs		(47)	(259)	(272)
Recoveries		90	10	15
Provision for (recovery of) loan losses		(368)	185	(1,514)
Ending Balance	2,911	879	2,911	1,204
Ending Balance:
Allowance for loan losses, Individually evaluated for impairment	133	22	133	173
Allowance for loan losses, Collectively evaluated for impairment	2,778	857	2,778	1,031
Loans:
Ending Balance	155,298	179,419	155,298	163,727
Loans, Individually evaluated for impairment	3,436	2,151	3,436	3,414
Loans, Collectively evaluated for impairment	151,862	177,268	151,862	160,313
Other Real Estate [Member]
Allowance for loan losses:
Beginning Balance		3,658	4,418	4,418
Charge-offs		(950)	(203)	(203)
Recoveries		2	340	509
Provision for (recovery of) loan losses		288	(131)	(1,066)
Ending Balance	4,424	2,998	4,424	3,658
Ending Balance:
Allowance for loan losses, Individually evaluated for impairment	914	596	914	1,456
Allowance for loan losses, Collectively evaluated for impairment	3,510	2,402	3,510	2,202
Loans:
Ending Balance	154,769	165,661	154,769	151,802
Loans, Individually evaluated for impairment	9,899	3,509	9,899	7,183
Loans, Collectively evaluated for impairment	144,870	162,152	144,870	144,619
Commercial and Industrial [Member]
Allowance for loan losses:
Beginning Balance		310	442	442
Charge-offs		(59)	(43)	(43)
Recoveries		69	16	18
Provision for (recovery of) loan losses		(68)	(58)	(107)
Ending Balance	357	252	357	310
Ending Balance:
Allowance for loan losses, Individually evaluated for impairment	36		36	33
Allowance for loan losses, Collectively evaluated for impairment	321	252	321	277
Loans:
Ending Balance	22,943	19,950	22,943	21,166
Loans, Individually evaluated for impairment	126	99	126	120
Loans, Collectively evaluated for impairment	22,817	19,851	22,817	21,046
Consumer and Other Loans [Member]
Allowance for loan losses:
Beginning Balance		143	99	99
Charge-offs		(364)	(251)	(318)
Recoveries		213	174	229
Provision for (recovery of) loan losses		198	136	133
Ending Balance	158	190	158	143
Ending Balance:
Allowance for loan losses, Collectively evaluated for impairment	158	190	158	143
Loans:
Ending Balance	11,818	11,448	11,818	12,240
Loans, Collectively evaluated for impairment	$ 11,818	$ 11,448	$ 11,818	$ 12,240

Financing receivable loans and leases receivable.

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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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