Cash, Cash Equivalents, and Investments (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 02, 2016	Oct. 04, 2015	Oct. 02, 2016	Oct. 04, 2015
Cash and Cash Equivalents [Abstract]
Gross realized gains on sale of investments	$ 55,000	$ 26,000	$ 280,000	$ 434,000
Gross realized losses on sale of investments	0	$ 7,000	97,000	$ 194,000
Maximum amount committed to invest in limited partnership			20,500,000
Contribution to limited partnership	19,886,000		$ 19,886,000
Investment expiration date			Dec. 31, 2017
Remaining amount of commitment in limited partnership	$ 614,000		$ 614,000
Contributions made during the period			0
Distributions received during the period			1,492,000
Partners' Capital Account, Return of Capital			942,000
Cost-method Investments, Realized Gains			$ 550,000