Fair Value Measurement (Quantitative Information About Level 3 Fair Value Measurements) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2012
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	62.00%
Third Party Pricing [Member] | REO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	13,817
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	36.00%
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	87,243
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	(38.00%)
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	30.00%
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	57.00%
Collateral depreciation	46.00%
Discounted Cash Flow [Member] | Impaired Mortgage Loans Held For Investment - TDRs [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	57,630
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	55.00%
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	42.00%