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Note 6 - Stockholders' Equity and Equity Compensation (Detail) - Binomial Option-Pricing Model Assumptions (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Weighted average grant-date fair value (in Dollars per share)	$ 12.92	$ 8.19
Volatility	49.80%	45.20%
Expected term (years)	7 years	7 years
Dividend yield	0.00%	0.00%
Risk-free rate	1.10%	1.50%

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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