Note 2. Fair Value of Financial Instruments (Detail) - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Commercial Real Estate Owner Occupied [Member] | Loans Receivable [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis	$ 2,407	$ 290
Commercial Real Estate Nonowner Occupied [Member] | Loans Receivable [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis	409	1,959
Commercial Real Estate Construction Financing Receivable [Member] | Loans Receivable [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis		587
Commercial Real Estate Construction Financing Receivable [Member] | Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis		1,814
Commercial and Industrial [Member] | Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis		1,134
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured on a recurring basis	1,501	5,513
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured on a recurring basis	1,005	2,559
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured on a recurring basis	91,253	77,598
Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member]
Commercial real estate:
Assets measured on a nonrecurring basis	$ 417	$ 430