Stock-Based Compensation - Summary of Change in Number of Non-Vested Options to Purchase Shares of Common Stock (Detail) (USD $)	3 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares, Nonvested, Beginning balance	305,500	303,000
Shares, Granted	100,000	180,500
Shares, Vested	(180,500)	(71,000)
Shares, Nonvested, Ending balance	225,000	412,500
Weighted Average Fair Value, Nonvested, Beginning balance	$ 7.14	$ 4.40
Weighted Average Fair Value, Granted	$ 8.55	$ 6.28
Weighted Average Fair Value, Vested	$ 6.28	$ 3.27
Weighted Average Fair Value, Nonvested, Ending balance	$ 8.45	$ 5.42