Cash, Cash Equivalents and Short-Term Investments and Long-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 70,721	$ 81,380
Unrealized Holdings Gains	33	39
Unrealized Holdings Losses	14	5
Fair Value	70,740	81,414
Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,384	5,819
Fair Value	7,384	5,819
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,330	14,302
Fair Value	14,330	14,302
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,714	20,121
Fair Value	21,714	20,121
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,751	48,953
Unrealized Holdings Gains	25	25
Unrealized Holdings Losses	3	3
Fair Value	32,773	48,975
Short-term Investments | Certificate of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000
Fair Value	1,000
Short-term Investments | Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,498	1,998
Unrealized Holdings Gains	2	1
Fair Value	1,500	1,999
Short-term Investments | Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,860	27,181
Unrealized Holdings Gains	11	13
Unrealized Holdings Losses	2	3
Fair Value	20,869	27,191
Short-term Investments | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,392	6,108
Unrealized Holdings Gains	10	4
Unrealized Holdings Losses	1
Fair Value	5,401	6,112
Short-term Investments | U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,001	13,506
Unrealized Holdings Gains	2	7
Fair Value	4,003	13,513
Short-term Investments | Variable rate demand notes ("VRDNs")
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		160
Fair Value		160
Other Long-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,256	12,306
Unrealized Holdings Gains	8	14
Unrealized Holdings Losses	11	2
Fair Value	16,253	12,318
Other Long-term Investments | Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,224	8,811
Unrealized Holdings Gains		12
Unrealized Holdings Losses	9
Fair Value	6,215	8,823
Other Long-term Investments | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,038	3,495
Unrealized Holdings Gains	2	2
Unrealized Holdings Losses		2
Fair Value	1,040	3,495
Other Long-term Investments | U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,994
Unrealized Holdings Gains	6
Unrealized Holdings Losses	2
Fair Value	$ 8,998