Fair Value of Financial Instruments - Summary of financial instruments (Details) - USD ($) $ in Thousands	Jan. 02, 2021	Dec. 28, 2019
Financial assets and liabilities measured at fair value on a recurring basis
Short-term investments	$ 521,963	$ 498,825
Recurring
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	95,520	93,704
Short-term investments	521,963	498,825
Other assets, net	5,340	5,647
Total assets at fair value	622,823	598,176
Recurring | Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	75,606	92,379
Recurring | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	4,919
Short-term investments	142,573	171,871
Recurring | Corporate debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	14,995	1,325
Short-term investments	379,390	326,954
Recurring | Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Other assets, net	5,340	5,647
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	77,961	92,379
Short-term investments	38,461	85,189
Total assets at fair value	116,422	177,568
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	75,606	92,379
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	2,355
Short-term investments	38,461	85,189
Recurring | Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	17,559	1,325
Short-term investments	483,502	413,636
Total assets at fair value	501,061	414,961
Recurring | Significant Other Observable Inputs (Level 2) | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	2,564
Short-term investments	104,112	86,682
Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Cash equivalents	14,995	1,325
Short-term investments	379,390	326,954
Recurring | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities measured at fair value on a recurring basis
Other assets, net	5,340	5,647
Total assets at fair value	5,340	5,647
Recurring | Significant Unobservable Inputs (Level 3) | Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Other assets, net	$ 5,340	$ 5,647