Fair Value (Assets Remeasured At Fair Value On Non-Recurring Basis) (Details) (Non-Recurring [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, Gain (loss) on financial instruments	$ (8,859)	$ (7,758)
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	102,632	120,392
As a percentage of total assets	2.60%	2.50%
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	102,632	120,392
As a percentage of total assets	2.60%	2.50%
REO [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	(350)	(772)
REO [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14,683	16,883
REO [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14,683	16,883
Impaired Mortgage Loans Held For Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	(8,509)	(6,986)
Impaired Mortgage Loans Held For Investment [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	87,949	103,509
Impaired Mortgage Loans Held For Investment [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 87,949	$ 103,509