Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Oct. 28, 2018	Oct. 29, 2017	Jan. 27, 2019	Jan. 28, 2018	Jan. 29, 2017
Accounting Policies [Abstract]
Aggregate net investments under cost method of accounting			$ 16,700	$ 38,100
Total equity method investments			2,700	3,400
Impairment of investments	$ 30,000	$ 4,300	$ 30,000	4,250	$ 0
Percent of realizable undiscounted cash flows used to determine useful life of acquired finite-lived intangible assets, minimum			90.00%
Advertising costs			$ 600	600	400
Recoveries from nonrecurring engineering services			$ 4,400	$ 5,400	$ 11,900