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Employee Benefit Plans - Narratives (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution maximum annual contribution for employee	75.00%
Defined contribution employer match	30.00%
Defined contribution employer match	5.00%
Employer contribution amount	$ 5.0	$ 4.8	$ 4.0
Multiemployer plan periodic withdraw liability	$ 0.1
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan contribution	5.00%
Multiemployer plans, red zone threshold	65.00%
Multiemployer plans, yellow zone threshold	80.00%
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer plans, yellow zone threshold	65.00%
Multiemployer plans, green zone threshold	80.00%

X

- Definition

The company contribution to a multiemployer plan as a percentage of total contributions.

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- Definition

Multiemployer Plan Periodic Withdraw Liability

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- Definition

Multiemployer Plans, Green Zone Threshold

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- Definition

Multiemployer Plans, Red Zone Threshold

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- Definition

Multiemployer Plans, Yellow Zone Threshold

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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- Definition

Percentage employer matches of the employee's percentage contribution matched.

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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