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Income Taxes - Narratives (Details) - USD ($) $ in Thousands | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jan. 27, 2018 | Jul. 29, 2017 | Jul. 30, 2016 | Jul. 25, 2015 | Jul. 26, 2014
Income Tax Contingency [Line Items] |  |  |  |  |
Tax Cuts and Jobs Act of 2017, adjustment to income tax liability | $ 32,200 |  |  |  |
Effective tax rate | 33.00% |  |  |  |
Cash tax benefit realized from option exercises and stock vestings | $ 7,800 |  |  |  |
Unrecognized tax benefits | 3,322 | $ 3,072 | $ 2,440 | $ 2,327 | $ 2,401
Payment of interest and penalties accrued | 1,200 | 1,200 | 1,000 |  |
Tax benefit from exercise of stock options | 7,800 |  |  |  |
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount |  | 6,000 | 4,500 | 4,000 |
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount |  | 1,300 | 2,500 | 2,800 |
Effective Income Tax Rate Reconciliation, Tax Credit, Amount | $ 1,596 | 0 | 0 | 0 |
Non deductible ana non taxable item |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Effective Income Tax Rate Reconciliation, Tax Credit, Amount |  | $ 1,000 | $ 700 | $ 500 |

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 + Details
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- Definition Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for qualified production activity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319 + Details
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