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Stock Options (Details)	12 Months Ended
Stock Options (Details)	Dec. 31, 2012	Dec. 31, 2011
Fair value of options granted to employees
Expected dividend yield	0.00%	0.00%
Expected term (employee grants)	6 years 3 months	6 years 3 months
Expected volatility	75.00%	49.00%
Minimum [Member]
Fair value of options granted to employees
Risk-free interest rate	0.62%	0.97%
Maximum [Member]
Fair value of options granted to employees
Risk-free interest rate	1.23%	3.05%

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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