Loans Receivable, Credit Quality for Loans and the Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Loan Portfolio Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	$ 3,717	$ 3,735	$ 4,365	$ 3,792
Allowance for Loan Losses, Charge-offs	303	49	1,061	109
Allowance for Loan Losses, Recoveries	39	9	50	12
Allowance for Loan Losses, Provision	156	450	255	450
Allowance for Loan Losses, Ending balance	3,609	4,145	3,609	4,145
Ending balance: individually evaluated for impairment					$ 36		$ 292
Ending balance: collectively evaluated for impairment					3,573		3,853
Allowance for Loan Losses	3,717	3,735	3,609	4,145	3,609	$ 4,365	4,145
Ending balance					398,493	409,845
Ending balance: individually evaluated for impairment					8,007	9,548
Ending balance: collectively evaluated for impairment					390,486	400,297
Home Equity Lines of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	104	107	93	104
Allowance for Loan Losses, Charge-offs		10		10
Allowance for Loan Losses, Provision	6	19	17	22
Allowance for Loan Losses, Ending balance	110	116	110	116
Ending balance: collectively evaluated for impairment					110		116
Allowance for Loan Losses	104	107	110	116	110	93	116
Ending balance					18,909	17,437
Ending balance: individually evaluated for impairment					361	400
Ending balance: collectively evaluated for impairment					18,548	17,037
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	566	363	1,298	330
Allowance for Loan Losses, Charge-offs			723
Allowance for Loan Losses, Recoveries	36	8	46	8
Allowance for Loan Losses, Provision	(44)	269	(63)	302
Allowance for Loan Losses, Ending balance	558	640	558	640
Ending balance: individually evaluated for impairment					1		272
Ending balance: collectively evaluated for impairment					557		368
Allowance for Loan Losses	566	363	558	640	558	1,298	640
Ending balance					46,330	46,076
Ending balance: individually evaluated for impairment					979	1,787
Ending balance: collectively evaluated for impairment					45,351	44,289
Commercial Real Estate Non-owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	1,320	1,297	1,372	1,380
Allowance for Loan Losses, Charge-offs			24
Allowance for Loan Losses, Provision	(135)	(6)	(163)	(89)
Allowance for Loan Losses, Ending balance	1,185	1,291	1,185	1,291
Ending balance: collectively evaluated for impairment					1,185		1,291
Allowance for Loan Losses	1,320	1,297	1,185	1,291	1,185	1,372	1,291
Ending balance					104,630	110,455
Ending balance: individually evaluated for impairment					2,150	2,187
Ending balance: collectively evaluated for impairment					102,480	108,268
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	621	731	552	713
Allowance for Loan Losses, Charge-offs				39
Allowance for Loan Losses, Provision	11	(12)	80	45
Allowance for Loan Losses, Ending balance	632	719	632	719
Ending balance: individually evaluated for impairment					2
Ending balance: collectively evaluated for impairment					630		719
Allowance for Loan Losses	621	731	632	719	632	552	719
Ending balance					76,862	69,647
Ending balance: individually evaluated for impairment					1,179	1,462
Ending balance: collectively evaluated for impairment					75,683	68,185
Commercial Real Estate 1-4 Family Investment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	270	395	303	369
Allowance for Loan Losses, Charge-offs	41	11	41	11
Allowance for Loan Losses, Provision	54	14	21	40
Allowance for Loan Losses, Ending balance	283	398	283	398
Ending balance: individually evaluated for impairment							14
Ending balance: collectively evaluated for impairment					283		384
Allowance for Loan Losses	270	395	283	398	283	303	398
Ending balance					25,229	25,398
Ending balance: individually evaluated for impairment					854	1,065
Ending balance: collectively evaluated for impairment					24,375	24,333
Commercial Land and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	93	113	202	115
Allowance for Loan Losses, Charge-offs	249		249
Allowance for Loan Losses, Provision	326	3	217	1
Allowance for Loan Losses, Ending balance	170	116	170	116
Ending balance: collectively evaluated for impairment					170		116
Allowance for Loan Losses	93	113	170	116	170	202	116
Ending balance					9,166	18,599
Ending balance: collectively evaluated for impairment					9,166	18,599
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	650	672	520	701
Allowance for Loan Losses, Charge-offs	8	12	8	27
Allowance for Loan Losses, Recoveries	2		2
Allowance for Loan Losses, Provision	(9)	20	121	6
Allowance for Loan Losses, Ending balance	635	680	635	680
Ending balance: individually evaluated for impairment					33		6
Ending balance: collectively evaluated for impairment					602		674
Allowance for Loan Losses	650	672	635	680	635	520	680
Ending balance					112,514	117,669
Ending balance: individually evaluated for impairment					2,484	2,647
Ending balance: collectively evaluated for impairment					110,030	115,022
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	30	19	25	15
Allowance for Loan Losses, Charge-offs	5	16	16	22
Allowance for Loan Losses, Recoveries	1	1	2	4
Allowance for Loan Losses, Provision	10	18	25	25
Allowance for Loan Losses, Ending balance	36	22	36	22
Ending balance: collectively evaluated for impairment					36		22
Allowance for Loan Losses	30	19	36	22	36	25	22
Ending balance					4,853	4,564
Ending balance: collectively evaluated for impairment					4,853	$ 4,564
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Beginning balance	63	38		65
Allowance for Loan Losses, Provision	(63)	125		98
Allowance for Loan Losses, Ending balance	0	163	0	163
Ending balance: collectively evaluated for impairment							163
Allowance for Loan Losses	$ 63	$ 38	$ 0	$ 163	$ 0		$ 163