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Shareholders' Equity (Details)	3 Months Ended		9 Months Ended
Shareholders' Equity (Details)	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair values of stock option grants estimated with weighted average assumptions
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected life	4 years	4 years	4 years	4 years
Expected volatility	73.00%	73.00%	73.00%	74.00%
Risk-free interest rate	0.50%	0.80%	0.60%	1.20%

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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