Fair Value Measurement (Assets Remeasured At Fair Value On Non-Recurring Basis) (Details) (Non-Recurring [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, Gain (loss) on financial instruments	$ (7,501)	$ (7,157)
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	103,678	131,312
As a percentage of total assets	2.70%	3.30%
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	103,678	131,312
As a percentage of total assets	2.70%	3.30%
REO [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	(203)	(485)
REO [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14,646	16,918
REO [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14,646	16,918
Impaired Mortgage Loans Held For Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	(7,298)	(6,672)
Impaired Mortgage Loans Held For Investment [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	89,032	114,394
Impaired Mortgage Loans Held For Investment [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 89,032	$ 114,394