Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jul. 31, 2011	Apr. 30, 2011
Current assets:
Restricted cash	$ 5,823	$ 5,821
Allowance for doubtful accounts receivable	$ 1,726	$ 2,147
Stockholders' equity:
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	65,811,531	65,710,531
Common stock, shares outstanding	64,611,531	64,510,531
Treasury stock, shares	1,200,000	1,200,000