XML 24 R52.htm IDEA: XBRL DOCUMENT

Stock-Based Compensation (Details 7)	3 Months Ended		9 Months Ended
Stock-Based Compensation (Details 7)	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Stock Options [Member]
Schedule of Employee Stock Purchase Plan, Valuation Assumptions
Expected life (in years)	4 years 6 months	4 years 6 months	4 years 6 months	5 years
Volatility	68.00%	70.00%	70.00%	69.00%
Interest rate	0.60%	0.90%	0.70%	1.70%
Dividend yield
Employee Stock [Member]
Schedule of Employee Stock Purchase Plan, Valuation Assumptions
Expected life (in years)	6 months	6 months	6 months	6 months
Volatility	52.00%	40.00%	62.00%	45.00%
Interest rate	0.10%	0.20%	0.10%	0.20%
Dividend yield

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.

+ References+ Details