Loans - Schedule of Impairment by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$ 9,137	$ 10,617
Recorded Investment with no Allowance	1,322	1,975
Recorded Investment with Allowance	7,387	8,235
Total Recorded Investment	8,709	10,210
Related Allowance	921	779
Average Recorded Investment	9,101	9,456
Interest Income Recognized	190	337
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,506	4,315
Recorded Investment with no Allowance	76
Recorded Investment with Allowance	3,436	4,329
Total Recorded Investment	3,512	4,329
Related Allowance	194	85
Average Recorded Investment	3,988	4,123
Interest Income Recognized	84	167
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,839	4,906
Recorded Investment with no Allowance	698	1,723
Recorded Investment with Allowance	2,805	2,849
Total Recorded Investment	3,503	4,572
Related Allowance	463	522
Average Recorded Investment	3,838	4,396
Interest Income Recognized	85	152
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	1,792	1,223
Recorded Investment with no Allowance	548	86
Recorded Investment with Allowance	1,146	1,057
Total Recorded Investment	1,694	1,143
Related Allowance	264	172
Average Recorded Investment	1,233	770
Interest Income Recognized	19	18
Construction & Land Development [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance		173
Recorded Investment with no Allowance		166
Total Recorded Investment		166
Average Recorded Investment	42	167
Interest Income Recognized	$ 2