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Stock-Based Compensation (Details)	3 Months Ended		6 Months Ended
Stock-Based Compensation (Details)	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Stock Options [Member]
Assumption of stock option's fair value
Expected life	4 years 2 months 12 days	4 years 6 months	4 years 6 months	4 years 6 months
Volatility	78.65%	77.49%	78.23%	76.97%
Risk free interest rate	0.74%	1.84%	0.85%	2.00%
Dividends
Employee Stock Purchase Plan [Member]
Assumption of stock option's fair value
Expected life	6 months	6 months	6 months	6 months
Volatility	55.93%	68.27%	62.74%	76.20%
Risk free interest rate	0.06%	0.21%	0.06%	0.20%
Dividends

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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