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Stock Option and Purchase Plans (Details)	12 Months Ended
Stock Option and Purchase Plans (Details)	Dec. 31, 2012	Dec. 31, 2011
Estimate fair value of options granted
Expected life (years)	4 years	4 years
Expected volatility	100.30%	91.30%
Risk-free interest rates	1.01%	2.24%
Expected dividend yield	1.62%	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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