Loans Receivable on Non-accrual Status (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	$ 14,003	$ 13,174
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	8,646	8,734
Commercial Non Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	854	835
Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	2,755	2,287
Automobiles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	11	19
Consumer Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	462	329
Residential 1-4 family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable on Non-accrual Status	$ 1,275	$ 970