Goodwill and Intangible Assets, net - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross	$ 19,175	$ 12,522
Accumulated Amortization	(6,300)	(3,367)
Write-offs	(1,114)	0	$ 0
Net	11,761	9,155
Capitalized internal-use software costs
Finite-Lived Intangible Assets [Line Items]
Gross	17,511	10,859
Accumulated Amortization	(5,172)	(2,487)
Write-offs	(1,077)	0
Net	11,262	8,372
Software licenses
Finite-Lived Intangible Assets [Line Items]
Gross	1,094	1,093
Accumulated Amortization	(558)	(314)
Write-offs	(37)	0
Net	499	779
Purchased developed technology
Finite-Lived Intangible Assets [Line Items]
Gross	570	570
Accumulated Amortization	(570)	(566)
Write-offs	0	0
Net	$ 0	$ 4