Stock-Based Compensation (Assumption and Weighted-Average Fair Values Used in the Black Scholes Model) (Details) (USD $)	6 Months Ended
Jun. 26, 2011 years	Jun. 27, 2010 years
Stock-Based Compensation
Weighted-average fair value of grants	$ 9.88	$ 7.39
Expected dividend yield	0.00%	0.00%
Expected volatility	49.85%	48.11%
Expected life (in years)	4.96	4.93
Risk-free interest rate	2.178%	1.893%

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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