Note 3. Investment Securities Available for Sale (Detail) - Gross Unrealized Losses and Fair Value of the Investments (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Securities in Unrealized Loss Position Less Than 12 Months Fair Value	$ 12,655	$ 5,622
Securities in Unrealized Loss Position Less Than 12 Months Unrealized Losses	158	200
Securities in Unrealized Loss Position Fair Value	12,655	5,622
Securities in Unrealized Loss Position Unrealized Losses	158	200
US States and Political Subdivisions Debt Securities [Member]
Securities in Unrealized Loss Position Less Than 12 Months Fair Value	5,748	1,812
Securities in Unrealized Loss Position Less Than 12 Months Unrealized Losses	65	10
Securities in Unrealized Loss Position Fair Value	5,748	1,812
Securities in Unrealized Loss Position Unrealized Losses	65	10
Corporate Debt Securities [Member]
Securities in Unrealized Loss Position Less Than 12 Months Fair Value	6,907	3,810
Securities in Unrealized Loss Position Less Than 12 Months Unrealized Losses	93	190
Securities in Unrealized Loss Position Fair Value	6,907	3,810
Securities in Unrealized Loss Position Unrealized Losses	$ 93	$ 190