Cash, Cash Equivalents, and Investments - Summary of Available-for-Sale Investments (Detail) $ in Thousands	Sep. 29, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 794,031
Gross unrealized gains	2,889
Gross unrealized losses	(207)
Fair value	796,713
Agency Bonds
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(25)
Agency Bonds | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	5,930
Gross unrealized gains	0
Gross unrealized losses	(25)
Fair value	5,905
Treasury Bills
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(91)
Treasury Bills | Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	105,254
Gross unrealized gains	212
Gross unrealized losses	(12)
Fair value	105,454
Treasury Bills | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	255,441
Gross unrealized gains	1,253
Gross unrealized losses	(79)
Fair value	256,615
Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(53)
Corporate Bonds | Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	86,990
Gross unrealized gains	222
Gross unrealized losses	(3)
Fair value	87,209
Corporate Bonds | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	167,464
Gross unrealized gains	584
Gross unrealized losses	(50)
Fair value	167,998
Asset-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(24)
Asset-Backed Securities | Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	89,226
Gross unrealized gains	359
Gross unrealized losses	(9)
Fair value	89,576
Asset-Backed Securities | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	56,636
Gross unrealized gains	195
Gross unrealized losses	(15)
Fair value	56,816
Sovereign Bonds
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(12)
Sovereign Bonds | Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	6,286
Gross unrealized gains	14
Gross unrealized losses	0
Fair value	6,300
Sovereign Bonds | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	15,969
Gross unrealized gains	43
Gross unrealized losses	(12)
Fair value	16,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	(2)
Municipal Bonds | Short-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	3,535
Gross unrealized gains	0
Gross unrealized losses	(2)
Fair value	3,533
Municipal Bonds | Long-Term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized cost	1,300
Gross unrealized gains	7
Gross unrealized losses	0
Fair value	$ 1,307