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Concentration of Credit Risk (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 27, 2013	Jul. 28, 2012	Jul. 30, 2011
Concentration Risk [Line Items]
Number of customers classified as highly concentrated	5
Customer Concentration Risk | Five Unnamed Customers
Concentration Risk [Line Items]
Concentration risk percentage	58.50%	59.60%	62.00%
Trade Accounts Receivable and Costs and Estimated Earnings | Customer Concentration Risk | AT&T
Concentration Risk [Line Items]
Concentration risk percentage	12.60%	9.20%
Accounts receivable, costs, and estimated earnings in excess of billings	$ 57.4	$ 24.7
Trade Accounts Receivable and Costs and Estimated Earnings | Customer Concentration Risk | CenturyLink
Concentration Risk [Line Items]
Concentration risk percentage	13.70%	17.70%
Accounts receivable, costs, and estimated earnings in excess of billings	62.6	47.6
Trade Accounts Receivable and Costs and Estimated Earnings | Customer Concentration Risk | Windstream Corporation
Concentration Risk [Line Items]
Concentration risk percentage	13.00%	13.20%
Accounts receivable, costs, and estimated earnings in excess of billings	59.4	35.4
Trade Accounts Receivable and Costs and Estimated Earnings | Customer Concentration Risk | Verizon
Concentration Risk [Line Items]
Concentration risk percentage	7.30%	11.30%
Accounts receivable, costs, and estimated earnings in excess of billings	$ 33.4	$ 30.5
Sales Revenue, Services, Net | Customer Concentration Risk | AT&T
Concentration Risk [Line Items]
Concentration risk percentage	15.50%	13.70%	21.10%
Sales Revenue, Services, Net | Customer Concentration Risk | CenturyLink
Concentration Risk [Line Items]
Concentration risk percentage	14.60%	13.60%	10.80%
Sales Revenue, Services, Net | Customer Concentration Risk | Comcast
Concentration Risk [Line Items]
Concentration risk percentage	10.90%	12.60%	14.30%
Sales Revenue, Services, Net | Customer Concentration Risk | Verizon
Concentration Risk [Line Items]
Concentration risk percentage	9.60%	11.30%	8.90%

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.

+ Details

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X

- Definition

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

+ References

No definition available.

+ Details

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X

- 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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