Mortgage Loans Held For Investment And Related Assets (Schedule Of Allowance For Impaired Loans) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Apr. 30, 2012
Financing Receivable, Impaired [Line Items]
Allowance for impaired loans	$ 10,586	$ 17,303
Based On Collateral Value Method [Member]
Financing Receivable, Impaired [Line Items]
Allowance for impaired loans	5,573	9,551
Based On Discounted Cash Flow Method [Member]
Financing Receivable, Impaired [Line Items]
Allowance for impaired loans	$ 5,013	$ 7,752