Debt (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		3 Months Ended
	Oct. 30, 2011	Oct. 31, 2010	Oct. 30, 2011	Oct. 31, 2010	Apr. 30, 2011	Oct. 30, 2011 Korean Loans [Member]	Oct. 30, 2011 Korean Loans Group 1 [Member]	Oct. 30, 2011 Korean Loans Group 2 [Member]	Jun. 29, 2011 Norwegian Loans [Member]	Oct. 30, 2011 Norwegian Loans [Member]	Jul. 31, 2011 Swedish Loan [Member]	Jun. 29, 2011 Swedish Loan [Member]
Debt Instrument [Line Items]
Number of Korean banks who lent $2.5 million							3
Short-term debt	$ 4,281,000		$ 4,281,000		$ 0		$ 2,500,000	$ 1,800,000
Debt variable rate basis								4-month KORIBOR
Debt basis spread								0.33%
Debt interest rate								4.00%
Debt stated interest rate												12.00%
Total									5,600,000	0	0	7,800,000
Debt stated interest rate, minimum						4.50%			5.25%
Debt stated interest rate, maximum						6.70%			6.00%
Loss on extinguishment of debt	$ 0		$ (419,000)	$ 0