Short-Term Investments - Summary of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 27, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 75,222	$ 80,212
Gross Unrealized Gains	60	62
Gross Unrealized Losses	(44)	(22)
Total short-term investments, Estimated Fair Value	75,238	80,252
State, municipal and local government agencies bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	35,412	40,426
Gross Unrealized Gains	41	38
Gross Unrealized Losses	(33)	(15)
Total short-term investments, Estimated Fair Value	35,420	40,449
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	30,112	33,483
Gross Unrealized Gains	16	20
Gross Unrealized Losses	(11)	(7)
Total short-term investments, Estimated Fair Value	30,117	33,496
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	5,694	2,299
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total short-term investments, Estimated Fair Value	5,694	2,299
U.S. federal government bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	4,004	4,004
Gross Unrealized Gains	3	4
Gross Unrealized Losses		0
Total short-term investments, Estimated Fair Value	$ 4,007	$ 4,008