Schedule of Reported Financial Assets and Liabilities (Detail) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Sep. 28, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,181,313	$ 1,199,751
Liabilities	2,146	2,230
Other Accrued Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	546
Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets		153
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	211,704	341,638
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	594,801	586,882
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	374,808	271,078
Long-term other accrued liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	1,600	2,230
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	212,711	296,263
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	200,612	283,107
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	12,099	13,156
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	968,602	903,488
Liabilities	546
Significant Other Observable Inputs (Level 2) | Other Accrued Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	546
Significant Other Observable Inputs (Level 2) | Other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets		153
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	11,092	58,531
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	594,801	586,882
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	362,709	257,922
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	1,600	2,230
Significant Unobservable Inputs (Level 3) | Long-term other accrued liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 1,600	$ 2,230