Reconciliation of Average Number of Common Shares and Common Share Equivalents Outstanding (Detail) - shares	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Average number of common shares outstanding	38,602,000	39,786,000	41,273,000
Incremental shares from assumed exercises of stock options			37,000
Average number of common shares and common share equivalents outstanding	38,602,000	39,786,000	41,310,000