Income Taxes - Narratives (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jan. 27, 2018	Jan. 25, 2020	Jan. 26, 2019	Jul. 29, 2017	Jul. 30, 2016
Income Tax Contingency [Line Items]
Effective tax rate	33.00%
Tax Cuts and Jobs Act of 2017, adjustment to income tax liability	$ 32,200
Tax benefit from exercise of stock options	7,800
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount				$ 6,000
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount				1,300
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	1,596	$ 2,801	$ 1,835	0
Unrecognized tax benefits	$ 3,322	4,742	3,786	3,072	$ 2,440
Payment of interest and penalties accrued		$ 1,700	$ 1,400
Non deductible ana non taxable item
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Amount				$ 1,000