Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jul. 02, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,620,211	$ 1,612,752
Liabilities	39,719	38,463
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	304
Other Accrued Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		131
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	598,349	307,884
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	809,338	871,024
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	212,501	433,843
Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	23	1
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	22,432	1,050
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	16,983	37,282
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	495,305	270,351
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	474,630	252,180
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	20,675	18,171
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	1,124,906	1,342,401
Liabilities	304	131
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	304
Significant Other Observable Inputs (Level 2) | Other Accrued Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		131
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	123,719	55,704
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	809,338	871,024
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	191,826	415,672
Significant Other Observable Inputs (Level 2) | Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	23	1
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	39,415	38,332
Significant Unobservable Inputs (Level 3) | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	22,432	1,050
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 16,983	$ 37,282