Loss Contingencies Arising From Representations And Warranties Of Our Discontinued Mortgage Operations (Narrative) (Details) (USD $)	9 Months Ended		12 Months Ended				57 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009	Jan. 31, 2013
Commitments And Contingencies [Line Items]
Percentage of fraud on originated loans	68.00%
Claims received for loans	$ 168,000,000		$ 1,092,000,000	$ 218,000,000	$ 145,000,000	$ 432,000,000	$ 2,055,000,000
Percentage of reviewed claims denied	94.00%
Loss severity rate	64.00%
Claims subject to review by SCC, amount	42,000,000						42,000,000
Reassertion of previously denied claims	20,000,000						20,000,000
Reserve for losses on repurchases	118,765,000	142,923,000	130,018,000	126,260,000			118,765,000
Net recorded loss provision		20,000,000
Loss severity rate, assumed	1.00%						1.00%
Denial rate, assumed	1.00%						1.00%
Increase in losses due to assumed 1% increase in loss severities and 1% decrease is denial rates	27,000,000
Minimum [Member]
Commitments And Contingencies [Line Items]
Number of days to respond to representation and warranty claims, in days	60 days
Maximum [Member]
Commitments And Contingencies [Line Items]
Number of days to respond to representation and warranty claims, in days	120 days
Private-Label Securitization Transactions [Member]
Commitments And Contingencies [Line Items]
Claims received for loans	144,000,000
Monoline Insurers [Member]
Commitments And Contingencies [Line Items]
Claims received for loans	15,000,000
Fannie Mae [Member]
Commitments And Contingencies [Line Items]
Claims received for loans	9,000,000
Loans Originated In 2006 And 2007 [Member]
Commitments And Contingencies [Line Items]
Percentage of loans originated	95.00%
Amount of loans originated	42,000,000,000						42,000,000,000
Loans Originated In 2006 And 2007 [Member] | Government-Sponsored Entity [Member]
Commitments And Contingencies [Line Items]
Percentage of loans originated	1.00%
Loans Originated In 2006 [Member]
Commitments And Contingencies [Line Items]
Value of defaulted loans	6,100,000,000						6,100,000,000
Loans Originated In 2007 [Member]
Commitments And Contingencies [Line Items]
Value of defaulted loans	2,700,000,000						2,700,000,000
Loans Paid In Full, Repurchased, Or Sold Without Recourse [Member]
Commitments And Contingencies [Line Items]
Percentage of reviewed claims denied	1.00%
Loans Liquidated [Member]
Commitments And Contingencies [Line Items]
Percentage of reviewed claims denied	1.00%
American International Group, Inc. [Member]
Commitments And Contingencies [Line Items]
Value of asseted claims	$ 650,000,000