Assets And Liabilities Measured At Fair Value (Fair Value Assets Measured At Fair Value On A Recurring And Non-Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, Gain (loss) on financial instruments	$ (4,351)	$ (10,590)
Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	434,579	222,282
As a percentage of total assets	9.00%	3.80%
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value
As a percentage of total assets
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	314,187	28,688
As a percentage of total assets	6.50%	0.50%
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets at fair value	120,392	193,594
As a percentage of total assets	2.50%	3.30%
Recurring [Member] | Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	2,956	(91)
Recurring [Member] | Mortgage-Backed Securities [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	306,475	19,927
Recurring [Member] | Mortgage-Backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Recurring [Member] | Mortgage-Backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	306,475	19,927
Recurring [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on investments	451	380
Recurring [Member] | Municipal Bonds [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,712	8,740
Recurring [Member] | Municipal Bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Recurring [Member] | Municipal Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,712	8,740
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)
Recurring [Member] | Trust Preferred Security [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		21
Recurring [Member] | Trust Preferred Security [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Recurring [Member] | Trust Preferred Security [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		21
Non-Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss), REO	(772)	(1,512)
Gain (loss), Impaired mortgage loans held for investment	(6,986)	(7,792)
Non-Recurring [Member] | Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO	16,883	19,532
Impaired mortgage loans held for investment	103,509	174,062
Non-Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO
Impaired mortgage loans held for investment
Non-Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO
Impaired mortgage loans held for investment
Non-Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
REO	16,883	19,532
Impaired mortgage loans held for investment	$ 103,509	$ 174,062