CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Income Statement [Abstract]
Net loss	$ (26,317)	$ (9,645)	$ (66,779)	$ (38,953)
Other comprehensive gain (loss) in relation to defined benefit plans, net of tax	(58)	(22)	(1,463)	87
Changes in unrealized gain (loss) on marketable securities, net of tax	373	(68)	210	(100)
Comprehensive loss	$ (26,002)	$ (9,735)	$ (68,032)	$ (38,966)