Fair Value Measurements - Fair Value of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2021	Aug. 01, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 160,441	$ 236,491
Gross Unrealized Gains	156	1,649
Gross Unrealized Losses	(16)	(6)
Fair Value	160,581	238,134
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	42,009	67,335
Gross Unrealized Gains	35	516
Gross Unrealized Losses	0	(1)
Fair Value	42,044	67,850
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,500	6,150
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	1,500	6,150
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,192	35,331
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	10,192	35,331
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,393	44,854
Gross Unrealized Gains	18	410
Gross Unrealized Losses	(9)	(4)
Fair Value	10,402	45,260
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	96,347	82,821
Gross Unrealized Gains	103	723
Gross Unrealized Losses	(7)	(1)
Fair Value	$ 96,443	$ 83,543

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
-Name Accounting Standards Codification
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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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