Stock-Based Compensation - Shares Available For Grant And Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Aug. 03, 2019	Jul. 28, 2018
Number of Options
Options vested and exercisable (in shares)	2,263,236
Options vested and expected to vest (in shares)	6,450,028
Weighted- Average Exercise Price
Options vested and exercisable (in dollars per share)	$ 9.48
Options vested and expected to vest (in dollars per share)	$ 14.40
Weighted- Average Remaining Contractual Life (in Years)
Options vested and exercisable, weighted-average remaining contractual life	6 years 9 months 7 days
Options vested and expected to vest, weighted-average remaining contractual life	7 years 7 months 9 days
Aggregate Intrinsic Value (in thousands)
Options vested and exercisable, aggregate intrinsic value	$ 35,009
Options vested and expected to vest, aggregate intrinsic value	$ 69,652
Options
Shares Available for Grant
Outstanding, beginning balance (in shares)	3,743,623
Authorized (in shares)	0
Granted (in shares)	(4,113,084)
Cancelled (in shares)	1,502,719
Outstanding, ending balance (in shares)	1,133,258	3,743,623
Two Thousand Eleven And Two Thousand Seventeen Incentive Plans
Number of Options
Outstanding, beginning balance (in shares)	9,052,160
Granted (in shares)	1,090,890
Exercised (in shares)	(2,198,655)
Cancelled (in shares)	(874,270)
Outstanding, ending balance (in shares)	7,070,125	9,052,160
Weighted- Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 11.74
Granted (in dollars per share)	24.77
Exercised (in dollars per share)	6.79
Cancelled (in dollars per share)	16.15
Outstanding, ending balance (in dollars per share)	$ 14.48	$ 11.74
Weighted- Average Remaining Contractual Life (in Years)
Outstanding, weighted-average remaining contractual life	7 years 8 months 19 days	8 years 2 months 23 days
Aggregate Intrinsic Value (in thousands)
Outstanding, aggregate intrinsic value	$ 73,861	$ 160,856

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available For Grant, Forfeited

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Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available For Grant, Granted

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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