Fair Value Measurements - Summary of Short-Term and Long-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$ 480,807	$ 353,109
Gross Unrealized Gains	1,009	582
Gross Unrealized Losses	(110)	(723)
Estimated Fair Value	481,706	352,968
U.S. Government and Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	182,354	89,617
Gross Unrealized Gains	123	27
Gross Unrealized Losses	(7)	(18)
Estimated Fair Value	182,470	89,626
Obligations of Government-Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	40,632	33,506
Gross Unrealized Gains	2	5
Gross Unrealized Losses	(3)	(1)
Estimated Fair Value	40,631	33,510
State and Municipal Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	48,914	51,573
Gross Unrealized Gains	113	82
Gross Unrealized Losses	(5)	(28)
Estimated Fair Value	49,022	51,627
Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	185,145	166,642
Gross Unrealized Gains	756	453
Gross Unrealized Losses	(83)	(675)
Estimated Fair Value	185,818	166,420
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	23,762	11,771
Gross Unrealized Gains	15	15
Gross Unrealized Losses	(12)	(1)
Estimated Fair Value	$ 23,765	$ 11,785