Assets And Liabilities Measured At Fair Value (Fair Value Assets And Liabilities Measured At Fair Value On A Recurring And Non-Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total gain (loss) on financial instruments	$ (3,260)	$ (8,217)	[1]
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	439,651	160,094	[1]
As a percentage of total assets	11.10%	3.70%
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
As a percentage of total assets	0.00%
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	308,339	29,903	[1]
As a percentage of total assets	7.80%	0.70%
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	131,312	130,191	[1]
As a percentage of total assets	3.30%	3.00%
Recurring [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	3,507	38	[1]
Recurring [Member] | Mortgage-Backed Securities [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	300,664	20,945	[1]
Recurring [Member] | Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	300,664	20,945	[1]
Recurring [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	390	550	[1]
Recurring [Member] | Municipal Bonds [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,675	8,937	[1]
Recurring [Member] | Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,675	8,937	[1]
Recurring [Member] | Trust Preferred Security [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments		(1,575)	[1]
Recurring [Member] | Trust Preferred Security [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		21	[1]
Recurring [Member] | Trust Preferred Security [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		21	[1]
Non-Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain or Loss On Real Estate Owned	(485)	(1,275)	[1]
Gain (loss) on impaired mortgage loans held for investment	(6,672)	(5,955)	[1]
Non-Recurring [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO	16,918	27,112	[1]
Impaired mortgage loans held for investment	114,394	103,079	[1]
Non-Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO	16,918	27,112	[1]
Impaired mortgage loans held for investment	$ 114,394	$ 103,079	[1]

[1] Prior year amounts have been restated to include only impaired mortgage loans and REO that were remeasured during the quarter and the gain (loss) on those remeasurements.