Mortgage Loans Held for Investment and Related Assets (Information Related to Impaired Loans) (Details) (USD $) In Thousands	Apr. 30, 2011	Apr. 30, 2010
Portfolio balance	$ 268,649	$ 310,861
Related allowance	80,849	77,611
Purchased from SCC [Member] | Portfolio Balance With Allowance [Member]
Portfolio balance	190,074
All Other [Member] | Portfolio Balance With Allowance [Member]
Portfolio balance	19,340
Portfolio Balance With Allowance [Member]
Portfolio balance	209,414	288,309
Purchased from SCC [Member] | Portfolio Balance Without Allowance [Member]
Portfolio balance	54,000
All Other [Member] | Portfolio Balance Without Allowance [Member]
Portfolio balance	5,235
Portfolio Balance Without Allowance [Member]
Portfolio balance	59,235	22,552
Purchased from SCC [Member]
Portfolio balance	244,074
Related allowance	75,373
All Other [Member]
Portfolio balance	24,575
Related allowance	$ 5,476