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Concentration of Credit Risk (Details) (USD $) In Millions, unless otherwise specified		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended					9 Months Ended			9 Months Ended
	Apr. 26, 2014 Customers	Apr. 26, 2014 Customer Concentration Risk Five Unnamed Customers	Apr. 27, 2013 Customer Concentration Risk Five Unnamed Customers	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk AT&T	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk AT&T	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk AT&T	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk AT&T	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk CenturyLink	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk CenturyLink	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk CenturyLink	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk CenturyLink	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk Comcast	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk Comcast	Apr. 26, 2014 Sales Revenue, Services, Net Customer Concentration Risk Comcast	Apr. 27, 2013 Sales Revenue, Services, Net Customer Concentration Risk Comcast	Apr. 26, 2014 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk AT&T	Apr. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk AT&T	Jul. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk AT&T	Apr. 26, 2014 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk CenturyLink	Apr. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk CenturyLink	Jul. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk CenturyLink	Apr. 26, 2014 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk Windstream Corporation	Apr. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk Windstream Corporation	Jul. 27, 2013 Trade Accounts Receivable and Costs and Estimated Earnings Customer Concentration Risk Windstream Corporation
Concentration Risk [Line Items]
Number of customers classified as highly concentrated	5
Concentration risk percentage		58.50%	58.60%	20.80%	17.40%	18.90%	15.00%	12.80%	14.30%	14.30%	14.30%	12.10%	10.10%	11.50%	11.20%	17.10%	12.60%		10.70%	13.70%		8.00%	13.00%
Accounts receivable, costs, and estimated earnings in excess of billings																$ 73.8		$ 57.4	$ 46.4		$ 62.6	$ 34.5		$ 59.4

X

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection. This also includes the amount included in cost of uncompleted contracts in excess of related billings, or unbilled accounts receivable.

+ References

No definition available.

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X

- Definition

The number of customers classified as highly concentrated in comparison to total revenue.

+ References

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13531-108611



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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