Balance Sheet Components - Components of Property And Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018
Property Plant And Equipment [Line Items]
Total property and equipment	$ 12,185	$ 11,971
Less: accumulated depreciation and amortization	(7,622)	(7,239)
Property and equipment, net	4,563	4,732
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment	$ 7,109	7,180
Website Development Costs
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	2 years
Total property and equipment	$ 3,323	2,579
Machinery and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,190	1,473
Office Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	5 years
Total property and equipment	$ 114	88
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, estimated lifes	Shorter of estimated life or remaining lease term
Total property and equipment	$ 449	$ 651
Minimum
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	3 years
Minimum \| Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	3 years
Minimum \| Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	3 years
Maximum
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	5 years
Maximum \| Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	4 years
Maximum \| Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, estimated life	5 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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