Cash, Cash Equivalents and Investments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011	Jul. 01, 2012
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains on the sale of investments	$ 342,000	$ 47,000	$ 1,669,000	$ 78,000
Gross realized Loss on the sale of investments	1,000	28,000	239,000	45,000
Maximum amount committed to invest in limited partnership			20,500,000
Investment expiration date			Dec. 31, 2013
Contribution to limited partnership	19,886,000		19,886,000
Remaining amount of commitment in limited partnership	614,000		614,000
Received a stock distribution					371,000
Recorded a realized loss on stock distribution	19,000
Shares were trading investment were sold	$ 352,000