Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 29, 2013	Dec. 31, 2012
Assets:
Money market instruments	$ 225	$ 5,076
Financial assets at fair value	408,973
Corporate Bonds [Member]
Assets:
Financial assets at fair value	210,341
Asset-Backed Securities [Member]
Assets:
Financial assets at fair value	69,928
Treasury Bills [Member]
Assets:
Financial assets at fair value	69,277
Sovereign Bonds [Member]
Assets:
Financial assets at fair value	29,923
Municipal Bonds [Member]
Assets:
Financial assets at fair value	28,005
Agency Bonds [Member]
Assets:
Financial assets at fair value	1,499
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Corporate stock	1,864
Money market instruments	225
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Assets:
Financial assets at fair value	210,341
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]
Assets:
Financial assets at fair value	69,928
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Treasury Bills [Member]
Assets:
Financial assets at fair value	69,277
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Sovereign Bonds [Member]
Assets:
Financial assets at fair value	29,923
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Municipal Bonds [Member]
Assets:
Financial assets at fair value	28,005
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Agency Bonds [Member]
Assets:
Financial assets at fair value	1,499
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Currency Forward Contracts [Member]
Assets:
Currency forward contracts	81
Liabilities:
Currency forward contracts	$ 64