Reconciliation of Average Number of Common Shares and Common Share Equivalents Outstanding (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Average number of common shares outstanding	41,450,000	41,935,000	41,744,000	41,907,000
Incremental shares from assumed exercises of stock options	41,000	75,000	51,000	97,000
Average number of common shares and common share equivalents outstanding	41,491,000	42,010,000	41,795,000	42,004,000