CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 75	$ 75
Shareholders' equity:
Preferred shares, par value (in dollars per share)	$ 0	$ 0
Preferred shares, shares authorized (in shares)	20,000	20,000
Preferred shares, shares issued (in shares)	0	0
Preferred shares, shares outstanding (in shares)	0	0
Common shares, par value (in dollars per share)	$ 0	$ 0
Common shares, shares authorized (in shares)	50,000	50,000
Common shares, shares issued (in shares)	12,963	12,963
Common shares, shares outstanding (in shares)	12,963	12,963