Income Taxes - Components of Net Deferred Tax Asset (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Deferred tax assets:
Allowance for loan losses	$ 6,358	$ 7,776
Deferred compensation	517	510
Retirement plans and salary continuation	1,667	1,585
Stock compensation	214	191
Off balance sheet reserves	177	204
Nonaccrual loan interest	178	341
Net unrealized losses on securities available for sale	0	2,592
Goodwill	161	184
Low income housing credit carryforward	1,348	1,022
Alternative minimum tax credit carryforward	706	664
Charitable contribution carryforward	320	333
Net operating loss carryforward	6,850	8,169
Other	232	178
Total deferred tax assets	18,728	23,749
Valuation allowance	(16,592)	(18,964)
Net deferred tax assets	2,136	4,785
Deferred tax liabilities:
Depreciation	986	1,116
Net unrealized gains on securities available for sale	27	0
Purchase accounting adjustments	439	495
Other	711	582
Total deferred tax liabilities	2,163	2,193
Net deferred tax asset (liability)	$ (27)	$ 2,592