Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Change in valuation allowance for deferred tax assets	$ (88,000)	$ (1,752,000)	$ 1,105,000
Change in valuation allowance	800,000	(1,900,000)	1,000,000
Capital loss carryforward	8,000	92,000
Internal Revenue Service (IRS) [Member]
Operating loss carryforwards	28,600,000
Domestic Tax Authority [Member]
Operating loss carryforwards	84,500,000
Foreign Tax Authority [Member]
Operating loss carryforwards	1,700,000
Income taxes payable	100,000
Income tax receivable	100,000
State and Local Jurisdiction [Member]
Operating loss carryforwards	8,200,000
Capital loss carryforward	200,000
Income taxes payable	0
Income tax receivable	$ 200,000
Maximum [Member] | Internal Revenue Service (IRS) [Member]
Operating loss carryforwards, expiration dates	2033
Maximum [Member] | Domestic Tax Authority [Member]
Operating loss carryforwards, expiration dates	2033
Maximum [Member] | State and Local Jurisdiction [Member]
Operating loss carryforwards, expiration dates	2033
Minimum [Member] | Internal Revenue Service (IRS) [Member]
Operating loss carryforwards, expiration dates	2014
Minimum [Member] | Domestic Tax Authority [Member]
Operating loss carryforwards, expiration dates	2014
Minimum [Member] | State and Local Jurisdiction [Member]
Operating loss carryforwards, expiration dates	2014