Summary of Significant Accounting Policies - Property, plant and equipment useful life (Details)	12 Months Ended
	Jan. 31, 2020
Computer and network equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	2 years
Computer and network equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Software, including capitalized software development costs
Property, Plant and Equipment [Line Items]
Useful life	3 years
Furniture and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Furniture and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	4 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life	10 years