Fair Value (Quantitative Information About Level 3 Fair Value Measurements) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	64.00%
Third Party Pricing [Member] | REO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	13,852
Third Party Pricing [Member] | Minimum [Member] | REO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	5.00%
Loss severity	0.00%
Third Party Pricing [Member] | Maximum [Member] | REO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	50.00%
Loss severity	100.00%
Third Party Pricing [Member] | Weighted Average [Member] | REO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	6.00%
Loss severity	52.00%
Collateral-Based [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Time to sell (in months)	24 months
Collateral-Based [Member] | Impaired Mortgage Loans Held For Investment - Non TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	87,926
Collateral-Based [Member] | Minimum [Member] | Impaired Mortgage Loans Held For Investment - Non TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	0.00%
Loss severity	0.00%
Collateral depreciation	(24.00%)
Collateral-Based [Member] | Maximum [Member] | Impaired Mortgage Loans Held For Investment - Non TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	45.00%
Loss severity	100.00%
Collateral depreciation	100.00%
Collateral-Based [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Time to sell (in months)	24 months
Collateral-Based [Member] | Weighted Average [Member] | Impaired Mortgage Loans Held For Investment - Non TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	7.00%
Loss severity	58.00%
Collateral depreciation	45.00%
Discounted Cash Flow [Member] | Impaired Mortgage Loans Held For Investment - TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	54,282
Discounted Cash Flow [Member] | Minimum [Member] | Impaired Mortgage Loans Held For Investment - TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	0.00%
Aged default performance	30.00%
Discounted Cash Flow [Member] | Maximum [Member] | Impaired Mortgage Loans Held For Investment - TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	21.00%
Aged default performance	50.00%
Discounted Cash Flow [Member] | Weighted Average [Member] | Impaired Mortgage Loans Held For Investment - TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	4.00%
Aged default performance	41.00%