CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2019	[1]	Jan. 31, 2018	[2]	Jan. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (134,612)		$ (154,960)		$ (151,787)	[2]
Other comprehensive (loss) income:
Changes in foreign currency translation adjustment	[3]	(265)		408		(37)	[2]
Net change in unrealized gain on available-for-sale investments	[2],[3]					2
Other comprehensive (loss) income	[3]	(265)		408		(36)	[2]
Comprehensive loss	[4]	$ (134,877)		$ (154,552)		$ (151,823)	[2]

[1] As reported under ASC Topic 606

[2] As reported under ASC Topic 605

[3] Tax effect was not material

[4] Due to rounding, numbers presented may not add up precisely to totals provided.