Loans - Amounts of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial, Total	$ 528,635	$ 505,189
Real Estate, Total	189,893	185,958
Consumer, Total	280,120	279,525
Mortgage warehouse	102,146	98,156
Total loans	1,100,794	1,068,828
Allowance for loan losses	(16,102)	(15,992)	(19,565)	(18,270)
Loans, net	1,084,692	1,052,836
Working Capital and Equipment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial, Total	253,939	241,569
Real Estate Including Agriculture [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial, Total	254,734	245,313
Tax Exempt Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial, Total	2,483	2,898
Other Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial, Total	17,479	15,409
1-4 Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real Estate, Total	185,428	181,393
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real Estate, Total	4,465	4,565
Recreation Consumer Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	5,107	4,839
Real Estate Home Improvement Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	31,139	30,729
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	96,682	96,924
Other Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	3,265	3,293
Consumer Loans Auto Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	140,147	139,915
Unsecured Debt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer, Total	$ 3,780	$ 3,825