Fair Value (Quantitative Information About Level 3 Fair Value Measurements) (Details) - Jul. 31, 2015 - USD ($) $ in Thousands	Total
Collateral-Based | Impaired Mortgage Loans Held For Investment - Non TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Time to sell (in months)	12 months
Collateral-Based | Impaired Mortgage Loans Held For Investment - TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 29,925
Collateral-Based | Minimum | Impaired Mortgage Loans Held For Investment - Non TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	0.00%
Loss severity	0.00%
Collateral depreciation	(128.00%)
Collateral-Based | Maximum | Impaired Mortgage Loans Held For Investment - Non TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	171.00%
Loss severity	100.00%
Collateral depreciation	100.00%
Collateral-Based | Weighted Average | Impaired Mortgage Loans Held For Investment - Non TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost to list/sell	10.00%
Loss severity	61.00%
Time to sell (in months)	12 months
Collateral depreciation	32.00%
Discounted Cash Flow | Impaired Mortgage Loans Held For Investment - Non TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 68,368
Discounted Cash Flow | Minimum | Impaired Mortgage Loans Held For Investment - TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	0.00%
Aged default performance	23.00%
Discounted Cash Flow | Maximum | Impaired Mortgage Loans Held For Investment - TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	23.00%
Aged default performance	36.00%
Discounted Cash Flow | Weighted Average | Impaired Mortgage Loans Held For Investment - TDRs
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	7.00%
Aged default performance	29.00%