Stock Plans (Details 1) (Employee Stock Purchase Plan, USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Employee Stock Purchase Plan
Schedule of stock options and employee stock purchase plan weighted-average assumptions
Expected dividends	0.00%	0.00%	0.00%	0.00%
Exercise price	$ 5.58	$ 16.19	$ 8.93	$ 18.01
Expected volatility	83.00%	33.00%	75.00%	43.00%
Average risk-free interest rate	0.16%	0.10%	0.12%	0.16%
Expected life/term (in years)	6 months	6 months	6 months	6 months
Fair value per share	$ 2.78	$ 3.94	$ 3.79	$ 5.00

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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