Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 28, 2020	Dec. 31, 2019
Assets:
Money market instruments	$ 50,222	$ 15,933
Financial assets at fair value	610,171
Corporate Bonds
Assets:
Financial assets at fair value	236,660
Treasury Bills
Assets:
Financial assets at fair value	230,692
Asset-Backed Securities
Assets:
Financial assets at fair value	91,610
Sovereign Bonds
Assets:
Financial assets at fair value	27,517
Agency Bonds
Assets:
Financial assets at fair value	22,054
Municipal Bonds
Assets:
Financial assets at fair value	1,638
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	50,222
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	0
Economic hedge forward contracts	46
Liabilities:
Economic hedge forward contracts	458
Contingent consideration liabilities	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate Bonds
Assets:
Financial assets at fair value	236,660
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Treasury Bills
Assets:
Financial assets at fair value	230,692
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-Backed Securities
Assets:
Financial assets at fair value	91,610
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Sovereign Bonds
Assets:
Financial assets at fair value	27,517
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Agency Bonds
Assets:
Financial assets at fair value	22,054
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Municipal Bonds
Assets:
Financial assets at fair value	1,638
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Liabilities:
Contingent consideration liabilities	$ 0	$ 1,153