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Share-Based Compensation - Weighted Average Assumptions Used for Employee Purchase Rights Granted Under Stock Purchase Plan (Detail) (USD $)	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair market value	39.31	35.78
Option price	37.34	33.99
Expected dividend yield	0.00%	0.00%
Expected volatility	17.00%	20.00%
Risk free interest rate	0.05%	0.02%

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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