Fair Value Measurements - Financial Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jan. 26, 2020	Jan. 27, 2019
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	$ 10,700	$ 3,105
Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Derivative financial instruments	0	69
Total financial assets	10,700	3,174
Total financial liabilities	2,108	6,675
Recurring | Level 1
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Derivative financial instruments	0	0
Total financial assets	0	0
Total financial liabilities	0	0
Recurring | Level 2
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Derivative financial instruments	0	69
Total financial assets	0	69
Total financial liabilities	0	0
Recurring | Level 3
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Derivative financial instruments	0	0
Total financial assets	10,700	3,105
Total financial liabilities	2,108	6,675
Recurring | Convertible debt
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	10,700	3,105
Recurring | Convertible debt | Level 1
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Convertible debt | Level 2
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	0	0
Recurring | Convertible debt | Level 3
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	10,700	3,105
AptoVision | Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	2,161
AptoVision | Recurring | Level 1
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	0
AptoVision | Recurring | Level 2
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	0
AptoVision | Recurring | Level 3
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	2,161
Cycleo | Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	2,108	4,514
Cycleo | Recurring | Level 1
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	0
Cycleo | Recurring | Level 2
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	0	0
Cycleo | Recurring | Level 3
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	$ 2,108	$ 4,514