CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (154,960)	$ (151,787)	$ (202,948)
Other comprehensive income (loss)*:
Changes in foreign currency translation adjustment	[1]	408	(37)	(26)
Net change in unrealized gain (loss) on available-for-sale investments	[1]		2	(2)
Other comprehensive income (loss)*:	[1]	408	(36)	(28)
Comprehensive loss**	[2]	$ (154,552)	$ (151,823)	$ (202,976)

[1] Tax effect was not material

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