Treasury Stock - Additional Information (Detail) - shares	12 Months Ended
	Jan. 31, 2015	Apr. 30, 2013
Equity, Class of Treasury Stock [Line Items]
Shares purchased under repurchase program	1,000,000
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares authorized to repurchase	1,000,000	1,000,000