Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (245,066)	$ (213,752)	$ (183,231)
Other comprehensive loss:
Change in unrealized net loss on available-for-sale securities	(562)	0	0
Comprehensive loss	$ (245,628)	$ (213,752)	$ (183,231)