Cash, Cash Equivalents, and Investments - Gross Unrealized Losses and Fair Values for Available-for-Sale Investments (Detail) $ in Thousands	Sep. 29, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 160,738
Unrealized losses, less than 12 months	(160)
Fair value, 12 months or greater	29,149
Unrealized losses, 12 months or greater	(47)
Total fair value	189,887
Total unrealized losses	(207)
Treasury Bills
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	108,863
Unrealized losses, less than 12 months	(91)
Fair value, 12 months or greater	0
Unrealized losses, 12 months or greater	0
Total fair value	108,863
Total unrealized losses	(91)
Agency Bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	5,905
Unrealized losses, less than 12 months	(25)
Fair value, 12 months or greater	0
Unrealized losses, 12 months or greater	0
Total fair value	5,905
Total unrealized losses	(25)
Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	23,263
Unrealized losses, less than 12 months	(17)
Fair value, 12 months or greater	20,713
Unrealized losses, 12 months or greater	(36)
Total fair value	43,976
Total unrealized losses	(53)
Asset-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	11,149
Unrealized losses, less than 12 months	(15)
Fair value, 12 months or greater	8,093
Unrealized losses, 12 months or greater	(9)
Total fair value	19,242
Total unrealized losses	(24)
Sovereign Bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	11,558
Unrealized losses, less than 12 months	(12)
Total fair value	11,558
Total unrealized losses	(12)
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	0
Unrealized losses, less than 12 months	0
Fair value, 12 months or greater	343
Unrealized losses, 12 months or greater	(2)
Total fair value	343
Total unrealized losses	$ (2)