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Stock Options, Stock Purchase Plan and Warrants (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair value of each stock option award granted
Expected term (in years)	3 years 8 months 12 days	3 years 7 months 6 days
Risk-free interest rate (%)	0.60%	1.18%
Expected volatility (%)	51.00%	55.00%
Dividend yield (%)	0.00%	0.00%
Weighted average fair value/share at grant date	$ 0.73	$ 0.51

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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