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Goodwill and Intangible Assets - Narratives (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jan. 26, 2019 | Oct. 27, 2018 | Jul. 28, 2018 | Apr. 28, 2018 | Jan. 27, 2018 | Oct. 28, 2017 | Jul. 29, 2017 | Apr. 29, 2017 | Jan. 28, 2017 | Oct. 29, 2016 | Jan. 27, 2018 | Jan. 28, 2017 | Jan. 26, 2019 | Jul. 29, 2017 | Jul. 30, 2016
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | $ 325,749 |  |  |  | $ 321,743 |  | $ 321,748 |  |  |  | $ 321,743 |  | $ 325,749 | $ 321,748 |
Amortization of intangible assets |  |  |  |  |  |  |  |  |  |  | 12,100 |  | $ 22,600 | 24,800 | $ 19,400
Change In Fair Value, Percentage |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |
Percentage Change in Fair Value Input |  |  |  |  |  |  |  |  |  |  |  |  | 10000.00% |  |
Revenues | 748,619 | $ 848,237 | $ 799,470 | $ 731,375 | $ 655,133 | $ 756,215 | $ 780,188 | $ 786,338 | $ 701,131 | $ 799,223 | $ 1,411,348 | $ 1,500,355 | $ 3,127,700 | $ 3,066,880 | $ 2,672,542
Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Usesul life |  |  |  |  |  |  |  |  |  |  |  |  | 11 years 1 month 6 days |  |
Trade names |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Usesul life |  |  |  |  |  |  |  |  |  |  |  |  | 8 years |  |
Non-compete agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Usesul life |  |  |  |  |  |  |  |  |  |  |  |  | 1 year 6 months |  |
Reporting Unit One [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | $ 5,700 |  |  |  |  |  |  |  |  |  |  |  | $ 5,700 |  |
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount | 18.00% |  |  |  |  |  |  |  |  |  |  |  | 18.00% |  |
Reporting Unit Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | $ 10,100 |  |  |  |  |  |  |  |  |  |  |  | $ 10,100 |  |
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount | 19.00% |  |  |  |  |  |  |  |  |  |  |  | 19.00% |  |
Sales Revenue, Services, Net [Member] | Windstream Corporation | Customer Concentration Risk [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | $ 13,200 |  |  |  |  |  |  |  |  |  |  |  | $ 13,200 |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  | $ 113,600 |  |

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