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Fair Value Measurements - Investment Impairments and Credit Loss Reserves (Details) - USD ($) | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | ---
Aug. 01, 2021 | Jul. 26, 2020 | Aug. 01, 2021 | Jul. 26, 2020 | Jan. 31, 2021 | Jan. 26, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Credit loss reserve for held-to-maturity debt securities and available for sale debt securities | $ 4,100,000 |  | $ 4,100,000 |  | $ 3,400,000 |
Increase in credit loss reserve for available-for-sale and held-to-maturity debt securities | $ 500,000 | $ 0 | $ 700,000 | $ 2,400,000 |  |
Impairment on non-marketable equity securities |  | $ 1,700,000 |  | $ 2,900,000 |  |
ASU 2016-13 | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Credit loss reserve on held-to-maturity securities |  |  |  |  |  | $ 400,000

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