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Weighted Average Black Scholes Fair Value Assumptions (Detail)
3 Months Ended
Mar. 24, 2018
Mar. 25, 2017
Black Scholes valuation assumptions [Abstract]    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 5 years 5 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 2.60% 2.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 12.00% 11.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate 2.70% 2.70%