Accounting Standards and Significant Accounting Policies - Revenue by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017		Oct. 31, 2018	Oct. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenue	$ 105,576	$ 66,911	[1]	$ 283,783	$ 179,495	[1]
United States
Disaggregation of Revenue [Line Items]
Total revenue	88,704	56,215		239,459	152,185
International
Disaggregation of Revenue [Line Items]
Total revenue	$ 16,872	$ 10,696		$ 44,324	$ 27,310

[1] See Note 2 for a summary of adjustments.