Segment Information (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2013 Location Segment	Apr. 30, 2012	Apr. 30, 2013 Europe	Jan. 31, 2013 Europe	Apr. 30, 2013 the Americas (excluding the United States)	Jan. 31, 2013 the Americas (excluding the United States)	Apr. 30, 2013 Asia	Jan. 31, 2013 Asia	Apr. 30, 2013 Middle East	Jan. 31, 2013 Middle East
Segment Reporting Information [Line Items]
Number of operating segments	2
Number of geographic locations	2
International Operations Contribution			17.40%	18.90%	11.40%	12.90%	8.20%	10.30%	9.20%	6.80%
Intercompany sales	$ 65.9	$ 55.1