Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	[2]	Jul. 31, 2018	Jul. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (60,123)	$ (58,411)	[1]	$ (124,427)	$ (115,570)	[3]
Other comprehensive income (loss):
Change in unrealized net gain (loss) on available-for-sale securities	(193)	165		(909)	282
Comprehensive loss	$ (60,316)	$ (58,246)		$ (125,336)	$ (115,288)

[1] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

[2] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

[3] * Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018