Reconciliation of Denominator Used in Calculation of Basic and Diluted Earnings or Loss Per Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013		Apr. 30, 2012
Earnings Per Share Disclosure [Line Items]
Net loss	$ (67,721)		$ (19,475)
Weighted-average shares outstanding for basic loss per share	588,385	[1]	552,600	[1]
Convertible senior notes	0		0
Employee stock awards	0		0
Warrants	0		0
Adjusted weighted-average shares outstanding and assumed conversions for diluted loss per share	588,385	[1]	552,600	[1]

[1] Prior period results have been adjusted to reflect the four-for-one stock split through a stock dividend which occurred in April 2013.