Earnings/Loss Per Share - Reconciliation of Denominator Used in Calculation of Basic and Diluted Loss Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Earnings Per Share [Abstract]
Net loss	$ (25,157)	$ (38,924)	$ (21,917)	$ (196,923)
Weighted-average shares outstanding for basic loss per share (in shares)	664,131	629,548	659,160	619,748
Convertible senior notes (in shares)	0	0	0	0
Employee stock awards (in shares)	0	0	0	0
Warrants (in shares)	0	0	0	0
Adjusted weighted-average shares outstanding and assumed conversions for diluted loss per share (in shares)	664,131	629,548	659,160	619,748