Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended							1 Months Ended	0 Months Ended	9 Months Ended
	Jan. 31, 2014	Apr. 30, 2013	Nov. 04, 2008	Jan. 31, 2014 Unused lines of Credit	Apr. 30, 2013 Unused lines of Credit	Nov. 04, 2008 Standby Letters of Credit	Jan. 31, 2014 Revolving Credit Facility Amendment Five	Jan. 31, 2014 Combined Letter Of Credit And Credit Card Services Subfacility	Jul. 31, 2007 Line of Credit	Feb. 21, 2014 Line of Credit Subsequent event	Jan. 31, 2014 Line of Credit Daily adjusting LIBOR rate
Debt Instrument [Line Items]
Revolving line of credit with a borrowing capacity							$ 30.0	$ 2.7
Line of credit facility current borrowing capacity percentage							100.00%
Loan and security agreement, issue date									Jul. 18, 2007
Loan and security agreement, expiration date									Jan. 31, 2015
Interest above daily adjusting LIBOR rate											2.50%
Letter of credit drawn	1.6	2.0								27.0
Unused revolving line of credit				28.4	28.0
Standby letter of credit in favor of its landlord			$ 0.5			$ 0.1