Fair Value Measurements - Narrative (Details) - USD ($)	12 Months Ended
	Jan. 26, 2020	Jan. 27, 2019	Jan. 28, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost-method investments, write down	$ 500,000
Available-for-sale, realized gain (loss)	(700,000)
Transfers of financial assets or liabilities between levels	0	$ 0
Impairment of investments	$ 1,211,000	30,000,000	$ 4,250,000
Fair value of investment		$ 0
Valuation Technique, Discounted Cash Flow | Measurement Input, Cap Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, measurement input		38.80%