Industry Segments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	3 Months Ended		6 Months Ended
	Oct. 31, 2014 Customer	Oct. 31, 2013 Customer	Oct. 31, 2014 Segment Customer Group	Oct. 31, 2014 Customer Concentration Risk Total revenues Minimum	Oct. 31, 2013 Customer Concentration Risk Total revenues Minimum	Oct. 31, 2014 Customer Concentration Risk Total revenues Minimum	Oct. 31, 2013 Home Depot Customer	Oct. 31, 2013 Home Depot Customer Concentration Risk Total revenues
Segment Reporting Information [Line Items]
Number of major business segments			3
Number of major product and service groups			4
Number of major customers	0	0	0				1
Percentage of total revenue				10.00%	10.00%	10.00%		10.00%
Total revenue							$ 5.0