Note 4. Loans and Allowance for Loan Losses (Detail) - Recorded Investment of Residential and Consumer Loans (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Automobile Loans [Member] | Performing Loans [Member]
Consumer Loans	$ 42,251	$ 45,677
Automobile Loans [Member] | Nonperforming Loans [Member]
Consumer Loans	33	25
Automobile Loans [Member]
Consumer Loans	42,284	45,702
Home Equity Loans [Member] | Performing Loans [Member]
Consumer Loans	19,159	20,502
Home Equity Loans [Member] | Nonperforming Loans [Member]
Consumer Loans	5	5
Home Equity Loans [Member]
Consumer Loans	19,164	20,507
Other Consumer Loans [Member] | Performing Loans [Member]
Consumer Loans	39,547	40,947
Other Consumer Loans [Member] | Nonperforming Loans [Member]
Consumer Loans	58	7
Other Consumer Loans [Member]
Consumer Loans	39,605	40,954
Residential Real Estate Loans [Member] | Performing Loans [Member]
Consumer Loans	230,449	235,515
Residential Real Estate Loans [Member] | Nonperforming Loans [Member]
Consumer Loans	2,681	2,975
Residential Real Estate Loans [Member]
Consumer Loans	233,130	238,490
Consumer Loans [Member] | Performing Loans [Member]
Consumer Loans	331,406	342,641
Consumer Loans [Member] | Nonperforming Loans [Member]
Consumer Loans	2,777	3,012
Consumer Loans [Member]
Consumer Loans	$ 334,183	$ 345,653