Note 6 - Stock-Based Compensation (Detail) - Fair Value of Each Stock Option Grant (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
Jan. 31, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 Minimum [Member]	Dec. 31, 2011 Maximum [Member]
Expected Volatility		34.12%	36.64%	33.61%	36.64%
Weighted-Average Volatility		34.12%	36.64%	35.60%
Expected Dividends		0.00%	0.00%	0.00%
Expected Term (In years)	10 years	7 years 6 months	7 years 6 months	6 years	7 years 6 months
Risk-Free Rate		1.31%	1.13%	1.82%
Weighted-Average Fair Value (Grant date) (in Dollars per share)		$ 8.61	$ 6.99	$ 5.07

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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-Name Accounting Standards Codification

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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