Leases (Schedule of Future Minimum Payments for Capital Leases And Noncancelable Operating Leases) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010
Leases [Abstract]
Capital leases, Future minimum payments due, 2013	$ 1,266
Capital leases, Future minimum payments due, 2014	1,262
Capital leases, Future minimum payments due, 2015	898
Capital leases, Future minimum payments due, 2016	721
Capital leases, Future minimum payments due, 2017	678
Capital leases, Future minimum payments due, Thereafter	12,462
Total minimum capital lease payments	17,287
Less amount representing interest	7,642
Present value of net minimum lease payments	9,645
Operating leases, Future minimum payments due, 2013	928
Operating leases, Future minimum payments due, 2014	739
Operating leases, Future minimum payments due, 2015	385
Operating leases, Future minimum payments due, 2016	199
Operating leases, Future minimum payments due, 2017	131
Operating leases, Future minimum payments due, Thereafter	481
Total minimum operating lease payments	2,863
Rent expense under operating leases	$ 1,269	$ 674	$ 438