Loans - Risk Category of Loans by Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	$ 576,343	$ 501,535
Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	44,301	40,143
Agricultural Real Estate [Member] | 1-2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	3,764	2,719
Agricultural Real Estate [Member] | 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	14,588	15,111
Agricultural Real Estate [Member] | 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	25,186	21,481
Agricultural Real Estate [Member] | 5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	729	794
Agricultural Real Estate [Member] | 6 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	34	38
Agricultural Real Estate [Member] | 7 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Agricultural Real Estate [Member] | 8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	65,449	57,770
Agricultural [Member] | 1-2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	9,263	5,022
Agricultural [Member] | 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	27,212	23,525
Agricultural [Member] | 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	28,974	29,188
Agricultural [Member] | 5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross		35
Agricultural [Member] | 6 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Agricultural [Member] | 7 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Agricultural [Member] | 8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	248,893	199,999
Commercial Real Estate [Member] | 1-2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	1,104	4,046
Commercial Real Estate [Member] | 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	55,060	42,467
Commercial Real Estate [Member] | 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	182,277	137,537
Commercial Real Estate [Member] | 5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	4,987	8,984
Commercial Real Estate [Member] | 6 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	5,092	6,295
Commercial Real Estate [Member] | 7 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	373	670
Commercial Real Estate [Member] | 8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	99,498	101,624
Commercial and Industrial [Member] | 1-2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	2,525	750
Commercial and Industrial [Member] | 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	21,610	21,750
Commercial and Industrial [Member] | 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	72,059	71,228
Commercial and Industrial [Member] | 5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	2,119	3,385
Commercial and Industrial [Member] | 6 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	758	2,202
Commercial and Industrial [Member] | 7 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	427	2,309
Commercial and Industrial [Member] | 8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Industrial Development Bonds [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	4,358	1,299
Industrial Development Bonds [Member] | 1-2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross		97
Industrial Development Bonds [Member] | 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	3,869	859
Industrial Development Bonds [Member] | 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross	489	343
Industrial Development Bonds [Member] | 5 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Industrial Development Bonds [Member] | 6 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Industrial Development Bonds [Member] | 7 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross
Industrial Development Bonds [Member] | 8 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans - Gross