Balance Sheet Components - Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018		Jan. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 27,825	$ 10,125
Accumulated Amortization	(7,707)	(5,068)
Net Carrying Amount	20,118	5,057	[1]
Intangible assets amortization expense	2,600	1,500		$ 1,400
Technology patents
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	10,125	10,125
Accumulated Amortization	(6,572)	(5,068)
Net Carrying Amount	$ 3,553	5,057
Weighted average remaining useful life	2 years 4 months 24 days
Developed technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 17,700	0
Accumulated Amortization	(1,135)	0
Net Carrying Amount	$ 16,565	$ 0
Weighted average remaining useful life	6 years 7 months 6 days

[1] * As adjusted to reflect the impact of the full retrospective adoption of ASC 606