Income Taxes - Reconciliation of Effective Tax Rate to US Federal Statutory Rate (Detail)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Tax Disclosure [Abstract]
United States federal income tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	0.60%	2.60%	0.70%
Meals and entertainment	(1.60%)	3.80%	0.60%
Stock compensation	(16.10%)	26.40%	4.80%
Executive compensation	(5.10%)	7.40%	2.90%
Non-deductible mark-to-market and interest adjustments	0.00%	(19.60%)	2.30%
United States federal and state credits	30.60%	(60.20%)	(15.20%)
Change in valuation allowance	6.40%	17.70%	(355.80%)
Foreign taxes and rate differential	21.70%	(17.80%)	11.90%
Tax rate changes	(0.30%)	(1.70%)	1.20%
Expiration of tax attributes	(12.70%)	21.00%
Other	(1.00%)	(0.80%)	0.70%
Total	56.50%	12.80%	(311.90%)