Significant Accounting Policies - Recently Adopted Accounting Guidance (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Jan. 27, 2020	Jan. 26, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in retained earnings	$ 671,196		$ 611,607
Deferred income tax assets	25,483		20,094
Prepaid taxes	(22,083)		(10,718)
Right-of-use assets	16,337		10,958
Lease liabilities	$ 17,147		11,458
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in retained earnings		$ (300)
Debt Securities, Held-to-maturity, Allowance for Credit Loss		$ 400	$ 400