Stock-Based Compensation - Summary of Assumptions Used to Estimate Fair Value of Stock Options Granted (Detail)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.33%	1.93%	2.57%
Expected volatility	32.73%	35.51%	44.88%
Expected life	4 years 8 months 12 days	4 years 6 months 22 days	4 years 3 months 4 days
Dividend yield	3.39%