CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (42,924)	$ (38,233)	$ (122,295)	$ (114,910)
Other comprehensive (loss) income*:
Changes in foreign currency translation adjustment	[1]	(88)	(12)	90	53
Net change in unrealized gain on available-for-sale investments	[1]				3
Other comprehensive (loss) income*:		(88)	(12)	90	56
Comprehensive loss		$ (43,012)	$ (38,245)	$ (122,205)	$ (114,854)

[1] Tax effect was not material