Major Customers (Details) (Revenue [Member], Customer Concentration Risk [Member])	3 Months Ended		6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
From unrelated customers [Member] | Gaming Business [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)	10.00%		10.00%
Number of major customers	1		1
From unrelated customers [Member] | No individual customer [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)		10.00%		10.00%
Number of major customers		0		0
From unrelated customers [Member] | Voting Business [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)	41.00%		28.00%
Number of major customers	1		1
From related customers [Member] | Gaming Business [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)	36.00%	61.00%	53.00%	50.00%
Number of major customers	1	1	2	1