XML 74 R60.htm IDEA: XBRL DOCUMENT v3.8.0.1
Weighted Average Assumptions used to Estimate Fair Value of Stock Options (Detail) - Times
12 Months Ended
Dec. 30, 2017
Dec. 31, 2016
Dec. 26, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility 36.20% 34.00% 34.20%
Risk-free interest rate 2.30% 2.16% 2.16%
Expected dividends 0.00% 0.00% 0.00%
Exercise factor 3.63 2.68 3.00
Discount for post-vesting restrictions 0.00% 0.00% 0.00%