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Equity and Stock Based Compensation Plans (Details)	3 Months Ended
Equity and Stock Based Compensation Plans (Details)	Mar. 30, 2013	Mar. 31, 2012
Stock Options [Member]
Assumption of stock option's fair value
Expected life	4 years 6 months	4 years 7 months 12 days
Volatility	73.12%	78.13%
Risk free interest rate	0.86%	0.88%
Dividends	0.00%	0.00%
Employee Stock Purchase Plan [Member]
Assumption of stock option's fair value
Expected life	6 months	6 months
Volatility	27.61%	55.93%
Risk free interest rate	0.11%	0.06%
Dividends	0.00%	0.00%

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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