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Note 10. Stock Based Compensation (Detail) - Fair Value of Option Assumptions	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Expected life (in years)		6 years 3 months
Expected forfeiture rate		0.00%
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Risk-free interest rate	1.60%	2.72%
Expected volatility	80.80%	80.70%
Expected life (in years)	6 years 109 days
Expected forfeiture rate	0.00%
Maximum [Member]
Risk-free interest rate	2.97%	2.84%
Expected volatility	82.30%	81.10%
Expected life (in years)	5 years
Expected forfeiture rate	7.50%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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