CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Income Statement [Abstract]
Net loss	$ (43,116)	$ (19,994)	$ (57,932)	$ (40,462)
Other comprehensive gain (loss) in relation to defined benefit plans, net of tax	(310)	(866)	87	(1,405)
Changes in unrealized gain (loss) on marketable securities, net of tax	(553)	(116)	1,086	(163)
Foreign currency translation adjustments, net of tax	6,289		6,289
Comprehensive loss	$ (37,690)	$ (20,976)	$ (50,470)	$ (42,030)