Fair Value Measurements - Financial Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jan. 27, 2019	Jan. 28, 2018
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	$ 3,105	$ 1,960
Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Derivative financial instruments	69	0
Total financial assets	3,174	1,960
Total financial liabilities	2,623	21,668
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	69	0
Total financial assets	69	0
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	3,105	1,960
Total financial liabilities	2,623	21,668
Recurring | Convertible debt
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Available-for-sale securities	3,105	1,960
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	3,105	1,960
AptoVision | Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	2,161	21,000
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	2,161	21,000
Cycleo | Recurring
Fair Value, Assets Measured On A Recurring Basis [Line Items]
Earn-out liability	462	668
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	$ 462	$ 668