Loans - Credit Risk Profile by Creditworthiness Category (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 642,353	$ 623,530
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	97,318	91,724
Commercial Real Estate - Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	17,036	17,617
Commercial Real Estate -Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	208,996	199,879
Pass / Watch [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	95,321	90,128
Pass / Watch [Member] | Commercial Real Estate - Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	17,036	17,399
Pass / Watch [Member] | Commercial Real Estate -Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	194,904	187,114
Criticized [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	872	876
Criticized [Member] | Commercial Real Estate - Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans		218
Criticized [Member] | Commercial Real Estate -Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,154	6,222
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,125	720
Substandard [Member] | Commercial Real Estate - Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans
Substandard [Member] | Commercial Real Estate -Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 6,938	$ 6,543