Income taxes - Schedule of Components of Provision for Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Current:
Federal	$ 0	$ 0	$ 0
State	(18)	(106)	(112)
Foreign	(8,766)	(5,371)	(3,097)
Total	(8,784)	(5,477)	(3,209)
Deferred:
Federal	0	0	917
State	0	0	0
Foreign	84	59	213
Total	84	59	1,130
Total provision for income taxes	$ (8,700)	$ (5,418)	$ (2,079)