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Stock Compensation Plans (Weighted-Average Underlying Assumptions Used) (Details) (Common Stock, USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Employee Stock Purchase Plan \| Employee stock purhcase rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.08%	0.14%
Volatility	60.40%	68.90%
Dividend yield	0.00%	0.00%
Expected life	6 months	6 months
Weighted-average grant date fair value	$ 1.09	$ 1.15
Equity Incentive Plan \| Stock option grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.20%	1.70%
Volatility	94.00%	94.50%
Dividend yield	0.00%	0.00%
Expected life	6 years 10 months 17 days	7 years 7 months 6 days
Weighted-average grant date fair value	$ 3.19	$ 3.70

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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