Shareholders' Equity (Weighted Average Assumptions Used in Stock Options Granted) (Details)	3 Months Ended	6 Months Ended
Jul. 01, 2011	Jul. 02, 2010	Jul. 01, 2011	Jul. 02, 2010
Shareholders' Equity
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected stock price volatility	43.70%	43.70%	43.60%	43.80%
Risk free interest rate	1.60%	1.80%	1.60%	1.80%
Expected life of option, in years	4.2	4.2	4.2	4.2

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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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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