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Stock-Based Compensation (Details)	3 Months Ended
Stock-Based Compensation (Details)	Mar. 31, 2013	Mar. 31, 2012
Schedule of fair value of each option award granted
Expected life	6 years 6 months 0 days	6 years 6 months 0 days
Expected volatility	76.83%	79.68%
Risk-free interest rate - Minimum	1.25%	1.40%
Risk-free interest rate - Maximum	1.38%	1.51%
Dividend yield	0.00%	0.00%

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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