Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2014	Dec. 31, 2013
Assets:
Money market instruments	$ 5,723	$ 520
Financial assets at fair value	419,737
Corporate Bonds
Assets:
Financial assets at fair value	224,352
Asset-Backed Securities
Assets:
Financial assets at fair value	74,885
Treasury Bills
Assets:
Financial assets at fair value	86,804
Sovereign Bonds
Assets:
Financial assets at fair value	20,417
Municipal Bonds
Assets:
Financial assets at fair value	11,779
Agency Bonds
Assets:
Financial assets at fair value	1,500
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	5,723
Foreign Currency Cash Flow Hedge Asset at Fair Value
Liabilities:
Currency forward contracts
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	0
Foreign Currency Cash Flow Hedge Asset at Fair Value	33
Liabilities:
Currency forward contracts	112
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate Bonds
Assets:
Financial assets at fair value	224,352
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-Backed Securities
Assets:
Financial assets at fair value	74,885
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Treasury Bills
Assets:
Financial assets at fair value	86,804
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Sovereign Bonds
Assets:
Financial assets at fair value	20,417
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Municipal Bonds
Assets:
Financial assets at fair value	11,779
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Agency Bonds
Assets:
Financial assets at fair value	$ 1,500