Deferred Revenue and Performance Obligations - Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Increase (Decrease) In Contract with Customer, Liability [Roll Forward]
Deferred revenue, beginning of period	$ 64,104	$ 38,169	$ 22,973
Billings	194,816	143,758	94,826
Revenue recognized	(166,351)	(117,823)	(79,630)
Deferred revenue, end of period	$ 92,569	$ 64,104	$ 38,169