Asset Disposal (Details) (USD $)	3 Months Ended	9 Months Ended
	Jan. 31, 2013	Jan. 31, 2013
Equipment [Member]
Asset Disposal [Line Items]
Gain (Loss) on Disposition of Assets	$ 46,000	$ 65,000
Inventory [Member]
Asset Disposal [Line Items]
Gain (Loss) on Disposition of Assets	0	40,000
Assets [Member]
Asset Disposal [Line Items]
Gain (Loss) on Disposition of Assets	$ 46,000	$ 105,000