Fair Value Measurements - Maturity Dates of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 31, 2012
Fair Value Measurements, Maturity Dates Of Investments [Line Items]
Amortized Cost	$ 402,351	$ 328,796
Estimated Fair Value	402,129	329,335
Less Than 1 Year [Member]
Fair Value Measurements, Maturity Dates Of Investments [Line Items]
Amortized Cost	173,413
Estimated Fair Value	173,542
1 to 5 Years [Member]
Fair Value Measurements, Maturity Dates Of Investments [Line Items]
Amortized Cost	220,002
Estimated Fair Value	220,184
6 to 10 Years [Member]
Fair Value Measurements, Maturity Dates Of Investments [Line Items]
Amortized Cost	8,936
Estimated Fair Value	8,403
Thereafter [Member]
Fair Value Measurements, Maturity Dates Of Investments [Line Items]
Amortized Cost	0
Estimated Fair Value	$ 0