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Stock-Based Compensation (Details 7)	3 Months Ended
Stock-Based Compensation (Details 7)	Mar. 31, 2013	Mar. 31, 2012
Stock Options [Member]
Schedule of stock option and employee stock purchase plan, valuation assumptions
Expected life (in years)	4 years 8 months 12 days	4 years 6 months 0 days
Volatility	69.00%	71.00%
Interest rate	0.80%	0.80%
Dividend yield
Employee Stock [Member]
Schedule of stock option and employee stock purchase plan, valuation assumptions
Expected life (in years)	6 months 0 days	6 months 0 days
Volatility	66.00%	72.00%
Interest rate	0.10%	0.10%
Dividend yield

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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