Earnings/Loss Per Share - Reconciliation of Denominator Used in Calculation of Basic and Diluted Loss Per Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Earnings Per Share [Abstract]
Net loss	$ (38,924)	$ (124,434)	$ (196,923)	$ (115,552)
Weighted-average shares outstanding for basic loss per share (in shares)	629,548	600,467	619,748	594,346
Convertible senior notes	0	0	0	0
Employee stock awards	0	0	0	0
Warrants	0	0	0	0
Adjusted weighted-average shares outstanding and assumed conversions for diluted loss per share (in shares)	629,548	600,467	619,748	594,346