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Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	1.72%	1.42%	1.57%
Expected volatility	119.00%	97.00%	107.00%
Expected option life (in years)	9 years 8 months 12 days	4 years 8 months 5 days	3 years 3 months 7 days

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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