Leases (Leased Property Under Capital Leases By Major Classes) (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2012	Apr. 30, 2011
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	$ 14,545	$ 14,538
Less accumulated amortization	4,378	3,918
Capital leased assets, net	10,167	10,620
Equipment [Member]
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	2,612	2,605
Real Estate [Member]
Leased Property Under Capital Leases By Major Classes [Line Items]
Capital leased assets, gross	$ 11,933	$ 11,933