Short-Term Investments - Summary of Short-Term Investments (Detail) - USD ($) $ in Thousands	Jul. 03, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 29,060	$ 31,845
Gross Unrealized Gains	4	19
Gross Unrealized Losses	(30)	(17)
Total short-term investments, Estimated Fair Value	29,034	31,847
State, municipal and local government agencies bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	8,868	13,946
Gross Unrealized Gains	4	16
Gross Unrealized Losses	0	(1)
Total short-term investments, Estimated Fair Value	8,872	13,961
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	20,192	17,899
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(30)	(16)
Total short-term investments, Estimated Fair Value	$ 20,162	$ 17,886