Cash, Cash Equivalents, and Investments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains on sale of investments	$ 512,000	$ 50,000
Gross realized losses on sale of investments	11,000	19,000
Maximum amount committed to invest in limited partnership	20,500,000
Contribution to limited partnership	19,886,000
Remaining amount of commitment in limited partnership	614,000
Investment expiration date	Dec. 31, 2015
Number of contributions made during the period	0
Distributions From Partnership During Period	$ 0