Leases (Leased Property Under Capital Leases By Major Classes) (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	$ 15,486	$ 14,545
Less accumulated amortization	4,900	4,378
Capital leased assets, net	10,586	10,167
Equipment [Member]
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	2,612	2,612
Real Estate [Member]
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	$ 12,874	$ 11,933