Major Customers (Details) (Revenue [Member], Customer Concentration Risk [Member])	3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)			10.00%
From Unrelated Customers [Member] | Gaming Business [Member]
Concentration Risk [Line Items]
Number of major customers	1		1
Concentration risk, percentage (in hundredths)	54.00%		21.00%
From Unrelated Customers [Member] | Voting Business [Member]
Concentration Risk [Line Items]
Number of major customers		1	1	1
Concentration risk, percentage (in hundredths)		48.00%	22.00%	30.00%
From Related Customers [Member] | Gaming Business [Member]
Concentration Risk [Line Items]
Number of major customers	1	1	2	1
Concentration risk, percentage (in hundredths)	30.00%	38.00%	47.00%	42.00%