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Weighted Average Input Assumptions and Resulting Fair Values (Detail)	12 Months Ended
	Dec. 31, 2011	Jan. 01, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years	6 years
Risk-free interest rate	1.20%	1.90%
Expected volatility	45.70%	44.20%
Dividend yield

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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