Loans and Allowance for Loan Losses - Summary of Recorded Investment Based on Delinquency Status (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	$ 902,299		$ 882,548		$ 843,088
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	401,591		414,005		381,852
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	88,646		68,705		76,570
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	66,507		64,983		64,524
Home Equity Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	123,076		122,830		126,958
Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	206,323		199,924		180,089
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ending loans balance	16,156		12,101		13,095
Commercial Credit Exposure
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	467,759		444,671
Total loans internally credit risk graded	(497,099)		(490,430)
Total loans not internally credit risk graded	(405,200)		(392,118)
Total ending loans balance	902,299		882,548
Commercial Credit Exposure | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	52		114
Commercial Credit Exposure | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	37		0
Commercial Credit Exposure | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	857		1,106
Commercial Credit Exposure | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	23,464		35,777
Commercial Credit Exposure | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	443,349		407,674
Commercial Credit Exposure | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(5,072)		(15,637)
Commercial Credit Exposure | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(24,268)		(29,357)
Commercial Credit Exposure | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		(765)
Commercial Credit Exposure | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(398,444)		(385,507)
Commercial Credit Exposure | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(1,511)		(1,695)
Commercial Credit Exposure | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(1,722)		(1,855)
Commercial Credit Exposure | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(3,523)		(3,061)
Commercial Credit Exposure | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	376,218		373,771
Total loans internally credit risk graded	(401,591)		(414,005)
Total loans not internally credit risk graded	0		0
Total ending loans balance	401,591		414,005
Commercial Credit Exposure | Commercial Real Estate | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Commercial Real Estate | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Commercial Real Estate | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	857		1,100
Commercial Credit Exposure | Commercial Real Estate | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	22,580		30,604
Commercial Credit Exposure | Commercial Real Estate | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	352,781		342,067
Commercial Credit Exposure | Commercial Real Estate | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(2,146)		(12,201)
Commercial Credit Exposure | Commercial Real Estate | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(23,227)		(27,268)
Commercial Credit Exposure | Commercial Real Estate | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		(765)
Commercial Credit Exposure | Commercial Real Estate | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Commercial Real Estate | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial Real Estate | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial Real Estate | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial Real Estate | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	85,339		64,690
Total loans internally credit risk graded	(88,646)		(68,705)
Total loans not internally credit risk graded	0		0
Total ending loans balance	88,646		68,705
Commercial Credit Exposure | Commercial | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	52		114
Commercial Credit Exposure | Commercial | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	37		0
Commercial Credit Exposure | Commercial | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		6
Commercial Credit Exposure | Commercial | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	271		4,547
Commercial Credit Exposure | Commercial | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	84,979		60,023
Commercial Credit Exposure | Commercial | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(2,891)		(3,394)
Commercial Credit Exposure | Commercial | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(416)		(621)
Commercial Credit Exposure | Commercial | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Commercial | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Commercial | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Commercial | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	0		0
Commercial Credit Exposure | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	6,202	[1]	6,210	[1]
Total loans internally credit risk graded	(6,862)	[1]	(7,720)	[1]
Total loans not internally credit risk graded	(59,645)	[1]	(57,263)	[1]
Total ending loans balance	66,507	[1]	64,983	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0	[1]	0	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0	[1]	0	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0	[1]	0	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	613	[1]	626	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	5,589	[1]	5,584	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	35	[1]	42	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	(625)	[1]	(1,468)	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0	[1]	0	[1]
Commercial Credit Exposure | Residential Real Estate | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0	[1]	0	[1]
Commercial Credit Exposure | Residential Real Estate | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(56,390)	[1]	(54,416)	[1]
Commercial Credit Exposure | Residential Real Estate | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(64)	[1]	(394)	[1]
Commercial Credit Exposure | Residential Real Estate | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(960)	[1]	(1,094)	[1]
Commercial Credit Exposure | Residential Real Estate | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(2,231)	[1]	(1,359)	[1]
Commercial Credit Exposure | Home Equity Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Total loans internally credit risk graded	0		0
Total loans not internally credit risk graded	(123,076)		(122,830)
Total ending loans balance	123,076		122,830
Commercial Credit Exposure | Home Equity Loans | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Home Equity Loans | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Home Equity Loans | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(120,359)		(120,196)
Commercial Credit Exposure | Home Equity Loans | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(932)		(630)
Commercial Credit Exposure | Home Equity Loans | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(707)		(494)
Commercial Credit Exposure | Home Equity Loans | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(1,078)		(1,510)
Commercial Credit Exposure | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Total loans internally credit risk graded	0		0
Total loans not internally credit risk graded	(206,323)		(199,924)
Total ending loans balance	206,323		199,924
Commercial Credit Exposure | Indirect | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Indirect | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Indirect | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Indirect | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Indirect | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Indirect | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Indirect | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Indirect | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Indirect | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Indirect | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(205,938)		(198,983)
Commercial Credit Exposure | Indirect | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(332)		(645)
Commercial Credit Exposure | Indirect | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(30)		(227)
Commercial Credit Exposure | Indirect | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(23)		(69)
Commercial Credit Exposure | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Total loans internally credit risk graded	0		0
Total loans not internally credit risk graded	(16,156)		(12,101)
Total ending loans balance	16,156		12,101
Commercial Credit Exposure | Consumer | Grade 1-Minimal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Consumer | Grade 2-Modest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Consumer | Grade 3-Better than average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Consumer | Grade 4-Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Consumer | Grade 5-Acceptable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Pass Credits	0		0
Commercial Credit Exposure | Consumer | Grade 6-Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Consumer | Grade 7-Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Consumer | Grade 8-Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Consumer | Grade 9-Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans internally credit risk graded	0		0
Commercial Credit Exposure | Consumer | Current loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(15,757)		(11,912)
Commercial Credit Exposure | Consumer | 30-59 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	(183)		(26)
Commercial Credit Exposure | Consumer | 60-89 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	25		40
Commercial Credit Exposure | Consumer | 90 days past due loans not internally risk graded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans not internally credit risk graded	$ (191)		$ (123)

[1] Residential loans with an internal commercial credit risk grade include loans that are secured by non-owner occupied 1-4 family residential properties and conventional 1-4 family residential properties.