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Goodwill and Intangible Assets - Narratives (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jul. 29, 2017	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 321,748	$ 321,748	$ 310,157	$ 271,653
Change in fair value, percentage			25.00%
Percentage change in fair value input			100.00%
Amortization of intangible assets		$ 24,800	$ 19,400	$ 16,700
Contract backlog
Finite-Lived Intangible Assets [Line Items]
Decrease in intangible assets	$ 5,200

X

- Definition

Change In Fair Value, Percentage

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Percentage Change in Fair Value Input

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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-Name Accounting Standards Codification
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-Section 45
-Paragraph 28
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-Publisher FASB
-Name Accounting Standards Codification
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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 increase (decrease) in carrying value of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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-Publisher FASB
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