Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 27, 2020	Dec. 31, 2019
Assets:
Money market instruments	$ 3,926	$ 15,933
Financial assets at fair value	714,708
Corporate Bonds
Assets:
Financial assets at fair value	259,887
Treasury Bills
Assets:
Financial assets at fair value	270,091
Asset-Backed Securities
Assets:
Financial assets at fair value	129,543
Sovereign Bonds
Assets:
Financial assets at fair value	24,496
Agency Bonds
Assets:
Financial assets at fair value	28,274
Municipal Bonds
Assets:
Financial assets at fair value	2,417
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	3,926
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Money market instruments	0
Economic hedge forward contracts	313
Liabilities:
Economic hedge forward contracts	121
Contingent consideration liabilities	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate Bonds
Assets:
Financial assets at fair value	259,887
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Treasury Bills
Assets:
Financial assets at fair value	270,091
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-Backed Securities
Assets:
Financial assets at fair value	129,543
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Sovereign Bonds
Assets:
Financial assets at fair value	24,496
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Agency Bonds
Assets:
Financial assets at fair value	28,274
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Municipal Bonds
Assets:
Financial assets at fair value	2,417
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Liabilities:
Contingent consideration liabilities	$ 0	$ 1,153