Short-Term Investments - Summary of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 28, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 78,501	$ 80,212
Gross Unrealized Gains	67	62
Gross Unrealized Losses	(21)	(22)
Total short-term investments, Estimated Fair Value	78,547	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	38,754	40,426
Gross Unrealized Gains	48	38
Gross Unrealized Losses	(17)	(15)
Total short-term investments, Estimated Fair Value	38,785	40,449
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	30,455	33,483
Gross Unrealized Gains	15	20
Gross Unrealized Losses	(4)	(7)
Total short-term investments, Estimated Fair Value	30,466	33,496
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	5,291	2,299
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total short-term investments, Estimated Fair Value	5,291	2,299
U.S. federal government bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	4,001	4,004
Gross Unrealized Gains	4	4
Gross Unrealized Losses	0	0
Total short-term investments, Estimated Fair Value	$ 4,005	$ 4,008