Reconciliation of Average Number of Common Shares and Common Share Equivalents Outstanding (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 24, 2016	Sep. 26, 2015
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Average number of common shares outstanding	42,039,000	43,446,000	42,223,000	43,975,000
Incremental shares from assumed exercises of stock options	131,000	161,000	118,000	159,000
Average number of common shares and common share equivalents outstanding	42,170,000	43,607,000	42,341,000	44,134,000