Commitments And Contingencies (Rollforward Of Reserve For Losses On Repurchases) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2012 Representation And Warranty Claims [Member]	Apr. 30, 2011 Representation And Warranty Claims [Member]	Apr. 30, 2010 Representation And Warranty Claims [Member]	Apr. 30, 2010 Indemnity Agreement Dated April 2008 [Member]	Apr. 30, 2009 Indemnity Agreement Dated April 2008 [Member]
Commitments And Contingencies [Line Items]
Reserve for losses on repurchases, beginning balance	$ 126,260	$ 188,200	$ 206,595	$ 126,260	$ 138,415	$ 156,659	$ 49,785	$ 49,936
Provisions	20,000
Payments on representation and warranty claims				(16,242)	(12,155)	(18,244)
Payments under indemnity agreement		(49,785)	(151)
Reserve for losses on repurchases, ending balance	$ 130,018	$ 126,260	$ 188,200	$ 130,018	$ 126,260	$ 138,415	$ 49,785	$ 49,936